[linux] 01/01: Update fix for CVE-2017-1000364 (Closes: #865303)

debian-kernel at lists.debian.org debian-kernel at lists.debian.org
Thu Jun 22 02:44:21 UTC 2017


This is an automated email from the git hooks/post-receive script.

benh pushed a commit to branch benh/stretch-security
in repository linux.

commit dceaef157450764c5b0f88294a7ddf9be5df636a
Author: Ben Hutchings <ben at decadent.org.uk>
Date:   Wed Jun 21 12:52:25 2017 +0100

    Update fix for CVE-2017-1000364 (Closes: #865303)
---
 debian/changelog                                   |   8 +
 ...d-me-mm-allow-to-configure-stack-gap-size.patch |  82 --
 .../all/mm-allow-to-configure-stack-gap-size.patch |  68 --
 .../mm-do-not-collapse-stack-gap-into-THP.patch    |  59 --
 .../bugfix/all/mm-enlarge-stack-guard-gap.patch    | 476 -----------
 ...under-sized-gap-in-unmapped_area-_topdown.patch |  27 +
 .../mm-larger-stack-guard-gap-between-vmas.patch   | 886 +++++++++++++++++++++
 ...-the-stack-gap-for-unpopulated-growing-vm.patch |  45 --
 ...mm-proc-drop-priv-parameter-from-is_stack.patch |  89 ---
 debian/patches/series                              |   8 +-
 10 files changed, 923 insertions(+), 825 deletions(-)

diff --git a/debian/changelog b/debian/changelog
index 6575ef4..2c241e8 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,11 @@
+linux (4.9.30-2+deb9u2) stretch-security; urgency=high
+
+  * Revert changes in version 4.9.30-2+deb9u1 (Closes: #865303)
+  * mm: larger stack guard gap, between vmas (CVE-2017-1000364)
+  * mm: Guard against under-sized gap in unmapped_area{,_topdown}()
+
+ -- Ben Hutchings <ben at decadent.org.uk>  Wed, 21 Jun 2017 12:52:12 +0100
+
 linux (4.9.30-2+deb9u1) stretch-security; urgency=high
 
   * mm: enlarge stack guard gap (CVE-2017-1000364)
diff --git a/debian/patches/bugfix/all/fold-me-mm-allow-to-configure-stack-gap-size.patch b/debian/patches/bugfix/all/fold-me-mm-allow-to-configure-stack-gap-size.patch
deleted file mode 100644
index b4f209b..0000000
--- a/debian/patches/bugfix/all/fold-me-mm-allow-to-configure-stack-gap-size.patch
+++ /dev/null
@@ -1,82 +0,0 @@
-From: Michal Hocko <mhocko at suse.com>
-Date: Fri, 16 Jun 2017 00:06:28 +0200
-Subject: fold me "mm: allow to configure stack gap size"
-Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-1000364
-
-- do not rely on is_stack when reporting the gap. show_map_vma has
-  all the information we need
----
- fs/proc/task_mmu.c | 19 +++++++++++++------
- 1 file changed, 13 insertions(+), 6 deletions(-)
-
-diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
-index f05faa18d8b6..ec7abc90b844 100644
---- a/fs/proc/task_mmu.c
-+++ b/fs/proc/task_mmu.c
-@@ -278,7 +278,7 @@ static int is_stack(struct vm_area_struct *vma)
- }
- 
- static void
--show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
-+show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid, bool *has_gap)
- {
- 	struct mm_struct *mm = vma->vm_mm;
- 	struct file *file = vma->vm_file;
-@@ -300,11 +300,17 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
- 	start = vma->vm_start;
- 	end = vma->vm_end;
- 	if (vma->vm_flags & VM_GROWSDOWN) {
--		if (stack_guard_area(vma, start))
-+		if (stack_guard_area(vma, start)) {
- 			start = min(end, start + stack_guard_gap);
-+			if (has_gap)
-+				*has_gap = true;
-+		}
- 	} else if (vma->vm_flags & VM_GROWSUP) {
--		if (stack_guard_area(vma, end))
-+		if (stack_guard_area(vma, end)) {
- 			end = max(start, end - stack_guard_gap);
-+			if (has_gap)
-+				*has_gap = true;
-+		}
- 	}
- 
- 	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
-@@ -361,7 +367,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
- 
- static int show_map(struct seq_file *m, void *v, int is_pid)
- {
--	show_map_vma(m, v, is_pid);
-+	show_map_vma(m, v, is_pid, NULL);
- 	m_cache_vma(m, v);
- 	return 0;
- }
-@@ -734,6 +740,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
- 		.mm = vma->vm_mm,
- 		.private = &mss,
- 	};
-+	bool has_gap = false;
- 
- 	memset(&mss, 0, sizeof mss);
- 
-@@ -764,7 +771,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
- 	/* mmap_sem is held in m_start */
- 	walk_page_vma(vma, &smaps_walk);
- 
--	show_map_vma(m, vma, is_pid);
-+	show_map_vma(m, vma, is_pid, &has_gap);
- 
- 	seq_printf(m,
- 		   "Size:           %8lu kB\n"
-@@ -807,7 +814,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
- 		   (vma->vm_flags & VM_LOCKED) ?
- 			(unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);
- 
--	if (is_stack(vma))
-+	if (has_gap)
- 		seq_printf(m, "Stack_Gap:      %8lu kB\n", stack_guard_gap >>10);
- 
- 	arch_show_smap(m, vma);
--- 
-2.11.0
-
diff --git a/debian/patches/bugfix/all/mm-allow-to-configure-stack-gap-size.patch b/debian/patches/bugfix/all/mm-allow-to-configure-stack-gap-size.patch
deleted file mode 100644
index f7fdd33..0000000
--- a/debian/patches/bugfix/all/mm-allow-to-configure-stack-gap-size.patch
+++ /dev/null
@@ -1,68 +0,0 @@
-From: Michal Hocko <mhocko at suse.com>
-Date: Wed, 14 Jun 2017 08:17:02 +0200
-Subject: mm: allow to configure stack gap size
-Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-1000364
-
-Add a kernel command line option (stack_guard_gap) to specify the stack
-gap size (in page unites) and export the value in /proc/<pid>/smaps for
-stack vmas. This might be used for special applications like CRIU/RR.
-
-Suggested-by: Linus Torvalds <torvalds at linux-foundation.org>
-Signed-off-by: Michal Hocko <mhocko at suse.com>
-[carnil: backport to 4.9, adjust location for documentation]
----
- Documentation/kernel-parameters.txt |  7 +++++++
- fs/proc/task_mmu.c                  |  3 +++
- mm/mmap.c                           | 13 +++++++++++++
- 3 files changed, 23 insertions(+)
-
---- a/Documentation/kernel-parameters.txt
-+++ b/Documentation/kernel-parameters.txt
-@@ -3932,6 +3932,13 @@ bytes respectively. Such letter suffixes
- 	spia_pedr=
- 	spia_peddr=
- 
-+	stack_guard_gap=	[MM]
-+			override the default stack gap protection. The value
-+			is in page units and it defines how many pages prior
-+			to (for stacks growing down) resp. after (for stacks
-+			growing up) the main stack are reserved for no other
-+			mapping. Default value is 256 pages.
-+
- 	stacktrace	[FTRACE]
- 			Enabled the stack tracer on boot up.
- 
---- a/fs/proc/task_mmu.c
-+++ b/fs/proc/task_mmu.c
-@@ -805,6 +805,9 @@ static int show_smap(struct seq_file *m,
- 		   (vma->vm_flags & VM_LOCKED) ?
- 			(unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);
- 
-+	if (is_stack(m->private, vma))
-+		seq_printf(m, "Stack_Gap:      %8lu kB\n", stack_guard_gap >>10);
-+
- 	arch_show_smap(m, vma);
- 	show_smap_vma_flags(m, vma);
- 	m_cache_vma(m, vma);
---- a/mm/mmap.c
-+++ b/mm/mmap.c
-@@ -2337,6 +2337,19 @@ int expand_downwards(struct vm_area_stru
- /* enforced gap between the expanding stack and other mappings. */
- unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
- 
-+static int __init cmdline_parse_stack_guard_gap(char *p)
-+{
-+	unsigned long val;
-+	char *endptr;
-+
-+	val = simple_strtoul(p, &endptr, 10);
-+	if (!*endptr)
-+		stack_guard_gap = val << PAGE_SHIFT;
-+
-+	return 0;
-+}
-+__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
-+
- /*
-  * Note how expand_stack() refuses to expand the stack all the way to
-  * abut the next virtual mapping, *unless* that mapping itself is also
diff --git a/debian/patches/bugfix/all/mm-do-not-collapse-stack-gap-into-THP.patch b/debian/patches/bugfix/all/mm-do-not-collapse-stack-gap-into-THP.patch
deleted file mode 100644
index abaf33a..0000000
--- a/debian/patches/bugfix/all/mm-do-not-collapse-stack-gap-into-THP.patch
+++ /dev/null
@@ -1,59 +0,0 @@
-From: Michal Hocko <mhocko at suse.com>
-Date: Wed, 14 Jun 2017 08:18:00 +0200
-Subject: mm: do not collapse stack gap into THP
-Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-1000364
-
-Oleg has noticed that khugepaged will happilly collapse stack vma (as
-long as it is not an early stack - see is_vma_temporary_stack) and
-it might effectively remove the stack gap area as well because a larger
-part of the stack vma is usually populated. The same applies to the
-page fault handler.
-
-Fix this by checking stack_guard_area when revalidating a VMA
-in hugepage_vma_revalidate.  We do not want to hook/replace
-is_vma_temporary_stack() check because THP might be still useful for
-stack, all we need is excluding the gap from collapsing into a THP.
-
-Also check the to-be-created THP in do_huge_pmd_anonymous_page to
-make sure it is completely outside of the gap area because we we could
-create THP covering the gap area.
-
-Noticed-by: Oleg Nesterov <oleg at redhat.com>
-Signed-off-by: Michal Hocko <mhocko at suse.com>
----
- mm/huge_memory.c | 3 +++
- mm/khugepaged.c  | 4 ++++
- 2 files changed, 7 insertions(+)
-
-diff --git a/mm/huge_memory.c b/mm/huge_memory.c
-index a84909cf20d3..a8b6881bb2a2 100644
---- a/mm/huge_memory.c
-+++ b/mm/huge_memory.c
-@@ -664,6 +664,9 @@ int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
- 
- 	if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
- 		return VM_FAULT_FALLBACK;
-+	if (stack_guard_area(vma, haddr) ||
-+			stack_guard_area(vma, haddr + HPAGE_PMD_SIZE))
-+		return VM_FAULT_FALLBACK;
- 	if (unlikely(anon_vma_prepare(vma)))
- 		return VM_FAULT_OOM;
- 	if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
-diff --git a/mm/khugepaged.c b/mm/khugepaged.c
-index 945fd1ca49b5..75d7fff36957 100644
---- a/mm/khugepaged.c
-+++ b/mm/khugepaged.c
-@@ -858,6 +858,10 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
- 		return SCAN_ADDRESS_RANGE;
- 	if (!hugepage_vma_check(vma))
- 		return SCAN_VMA_CHECK;
-+
-+	/* never try to collapse stack gap */
-+	if (stack_guard_area(vma, hstart) || stack_guard_area(vma, hend))
-+		return SCAN_ADDRESS_RANGE;
- 	return 0;
- }
- 
--- 
-2.11.0
-
diff --git a/debian/patches/bugfix/all/mm-enlarge-stack-guard-gap.patch b/debian/patches/bugfix/all/mm-enlarge-stack-guard-gap.patch
deleted file mode 100644
index b9d8770..0000000
--- a/debian/patches/bugfix/all/mm-enlarge-stack-guard-gap.patch
+++ /dev/null
@@ -1,476 +0,0 @@
-From: Michal Hocko <mhocko at suse.com>
-Date: Wed, 14 Jun 2017 08:16:54 +0200
-Subject: mm: enlarge stack guard gap
-Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-1000364
-
-Stack guard page is a useful feature to reduce a risk of stack smashing
-into a different mapping. We have been using a single page gap which
-is sufficient to prevent having stack adjacent to a different mapping.
-But this seems to be insufficient in the light of the stack usage in
-the userspace. E.g. glibc uses as large as 64kB alloca() in many
-commonly used functions. Others use constructs liks gid_t
-buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN.
-
-This will become especially dangerous for suid binaries and the default
-no limit for the stack size limit because those applications can be
-tricked to consume a large portion of the stack and a single glibc call
-could jump over the guard page. These attacks are not theoretical,
-unfortunatelly.
-
-Make those attacks less probable by increasing the stack guard gap
-to 1MB (on systems with 4k pages but make it depend on the page size
-because systems with larger base pages might cap stack allocations in
-the PAGE_SIZE units) which should cover larger alloca() and VLA stack
-allocations. It is obviously not a full fix because the problem is
-somehow inherent but it should reduce attack space a lot. One could
-argue that the gap size should be configurable from the userspace but
-that can be done later on top when somebody finds that the new 1MB is
-not suitable or even wrong for some special case applications.
-
-Implementation wise, get rid of check_stack_guard_page and move all the
-guard page specific code to expandable_stack_area which always tries to
-guarantee the gap. do_anonymous_page then just calls expand_stack. Also
-get rid of stack_guard_page_{start,end} and replace them with
-stack_guard_area to handle stack population and /proc/<pid>/[s]maps.
-
-This should clean up the code which is quite scattered currently
-and therefore justify the change.
-
-Signed-off-by: Michal Hocko <mhocko at suse.com>
-[carnil: backport for 4.9: vmf->address -> fe->address]
----
- arch/ia64/mm/fault.c |   2 +-
- fs/exec.c            |   8 ++-
- fs/proc/task_mmu.c   |  11 ++--
- include/linux/mm.h   |  40 +++-----------
- mm/gup.c             |   4 +-
- mm/memory.c          |  38 ++-----------
- mm/mmap.c            | 152 +++++++++++++++++++++++++++++++++++++++++----------
- 7 files changed, 152 insertions(+), 103 deletions(-)
-
---- a/arch/ia64/mm/fault.c
-+++ b/arch/ia64/mm/fault.c
-@@ -224,7 +224,7 @@ retry:
- 		 */
- 		if (address > vma->vm_end + PAGE_SIZE - sizeof(long))
- 			goto bad_area;
--		if (expand_upwards(vma, address))
-+		if (expand_upwards(vma, address, 0))
- 			goto bad_area;
- 	}
- 	goto good_area;
---- a/fs/exec.c
-+++ b/fs/exec.c
-@@ -196,7 +196,7 @@ static struct page *get_arg_page(struct
- 
- #ifdef CONFIG_STACK_GROWSUP
- 	if (write) {
--		ret = expand_downwards(bprm->vma, pos);
-+		ret = expand_downwards(bprm->vma, pos, 0);
- 		if (ret < 0)
- 			return NULL;
- 	}
-@@ -218,6 +218,12 @@ static struct page *get_arg_page(struct
- 		unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
- 		struct rlimit *rlim;
- 
-+		/*
-+		 * GRWOSUP doesn't really have any gap at this stage because we grow
-+		 * the stack down now. See the expand_downwards above.
-+		 */
-+		if (!IS_ENABLED(CONFIG_STACK_GROWSUP))
-+			size -= stack_guard_gap;
- 		acct_arg_size(bprm, size / PAGE_SIZE);
- 
- 		/*
---- a/fs/proc/task_mmu.c
-+++ b/fs/proc/task_mmu.c
-@@ -302,11 +302,14 @@ show_map_vma(struct seq_file *m, struct
- 
- 	/* We don't show the stack guard page in /proc/maps */
- 	start = vma->vm_start;
--	if (stack_guard_page_start(vma, start))
--		start += PAGE_SIZE;
- 	end = vma->vm_end;
--	if (stack_guard_page_end(vma, end))
--		end -= PAGE_SIZE;
-+	if (vma->vm_flags & VM_GROWSDOWN) {
-+		if (stack_guard_area(vma, start))
-+			start += stack_guard_gap;
-+	} else if (vma->vm_flags & VM_GROWSUP) {
-+		if (stack_guard_area(vma, end))
-+			end -= stack_guard_gap;
-+	}
- 
- 	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
- 	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
---- a/include/linux/mm.h
-+++ b/include/linux/mm.h
-@@ -1378,39 +1378,11 @@ int clear_page_dirty_for_io(struct page
- 
- int get_cmdline(struct task_struct *task, char *buffer, int buflen);
- 
--/* Is the vma a continuation of the stack vma above it? */
--static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
--{
--	return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
--}
--
- static inline bool vma_is_anonymous(struct vm_area_struct *vma)
- {
- 	return !vma->vm_ops;
- }
- 
--static inline int stack_guard_page_start(struct vm_area_struct *vma,
--					     unsigned long addr)
--{
--	return (vma->vm_flags & VM_GROWSDOWN) &&
--		(vma->vm_start == addr) &&
--		!vma_growsdown(vma->vm_prev, addr);
--}
--
--/* Is the vma a continuation of the stack vma below it? */
--static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
--{
--	return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
--}
--
--static inline int stack_guard_page_end(struct vm_area_struct *vma,
--					   unsigned long addr)
--{
--	return (vma->vm_flags & VM_GROWSUP) &&
--		(vma->vm_end == addr) &&
--		!vma_growsup(vma->vm_next, addr);
--}
--
- int vma_is_stack_for_current(struct vm_area_struct *vma);
- 
- extern unsigned long move_page_tables(struct vm_area_struct *vma,
-@@ -2149,16 +2121,22 @@ void page_cache_async_readahead(struct a
- 				pgoff_t offset,
- 				unsigned long size);
- 
-+extern unsigned long stack_guard_gap;
- /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
- extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
-+extern int stack_guard_area(struct vm_area_struct *vma, unsigned long address);
- 
- /* CONFIG_STACK_GROWSUP still needs to to grow downwards at some places */
- extern int expand_downwards(struct vm_area_struct *vma,
--		unsigned long address);
-+		unsigned long address, unsigned long gap);
-+unsigned long expandable_stack_area(struct vm_area_struct *vma,
-+		unsigned long address, unsigned long *gap);
-+
- #if VM_GROWSUP
--extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
-+extern int expand_upwards(struct vm_area_struct *vma,
-+		unsigned long address, unsigned long gap);
- #else
--  #define expand_upwards(vma, address) (0)
-+  #define expand_upwards(vma, address, gap) (0)
- #endif
- 
- /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
---- a/mm/gup.c
-+++ b/mm/gup.c
-@@ -371,9 +371,7 @@ static int faultin_page(struct task_stru
- 	if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
- 		return -ENOENT;
- 	/* For mm_populate(), just skip the stack guard page. */
--	if ((*flags & FOLL_POPULATE) &&
--			(stack_guard_page_start(vma, address) ||
--			 stack_guard_page_end(vma, address + PAGE_SIZE)))
-+	if ((*flags & FOLL_POPULATE) && stack_guard_area(vma, address))
- 		return -ENOENT;
- 	if (*flags & FOLL_WRITE)
- 		fault_flags |= FAULT_FLAG_WRITE;
---- a/mm/memory.c
-+++ b/mm/memory.c
-@@ -2698,39 +2698,7 @@ out_release:
- 	return ret;
- }
- 
--/*
-- * This is like a special single-page "expand_{down|up}wards()",
-- * except we must first make sure that 'address{-|+}PAGE_SIZE'
-- * doesn't hit another vma.
-- */
--static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
--{
--	address &= PAGE_MASK;
--	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
--		struct vm_area_struct *prev = vma->vm_prev;
--
--		/*
--		 * Is there a mapping abutting this one below?
--		 *
--		 * That's only ok if it's the same stack mapping
--		 * that has gotten split..
--		 */
--		if (prev && prev->vm_end == address)
--			return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
--
--		return expand_downwards(vma, address - PAGE_SIZE);
--	}
--	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
--		struct vm_area_struct *next = vma->vm_next;
- 
--		/* As VM_GROWSDOWN but s/below/above/ */
--		if (next && next->vm_start == address + PAGE_SIZE)
--			return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
--
--		return expand_upwards(vma, address + PAGE_SIZE);
--	}
--	return 0;
--}
- 
- /*
-  * We enter with non-exclusive mmap_sem (to exclude vma changes,
-@@ -2749,8 +2717,10 @@ static int do_anonymous_page(struct faul
- 		return VM_FAULT_SIGBUS;
- 
- 	/* Check if we need to add a guard page to the stack */
--	if (check_stack_guard_page(vma, fe->address) < 0)
--		return VM_FAULT_SIGSEGV;
-+	if (stack_guard_area(vma, fe->address)) {
-+		if (expand_stack(vma, fe->address) < 0)
-+			return VM_FAULT_SIGSEGV;
-+	}
- 
- 	/*
- 	 * Use pte_alloc() instead of pte_alloc_map().  We can't run
---- a/mm/mmap.c
-+++ b/mm/mmap.c
-@@ -2151,7 +2151,8 @@ find_vma_prev(struct mm_struct *mm, unsi
-  * update accounting. This is shared with both the
-  * grow-up and grow-down cases.
-  */
--static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
-+static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow,
-+		unsigned long gap)
- {
- 	struct mm_struct *mm = vma->vm_mm;
- 	struct rlimit *rlim = current->signal->rlim;
-@@ -2164,7 +2165,7 @@ static int acct_stack_growth(struct vm_a
- 	/* Stack limit test */
- 	actual_size = size;
- 	if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
--		actual_size -= PAGE_SIZE;
-+		actual_size -= gap;
- 	if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
- 		return -ENOMEM;
- 
-@@ -2200,7 +2201,7 @@ static int acct_stack_growth(struct vm_a
-  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
-  * vma is the last one with address > vma->vm_end.  Have to extend vma.
-  */
--int expand_upwards(struct vm_area_struct *vma, unsigned long address)
-+int expand_upwards(struct vm_area_struct *vma, unsigned long address, unsigned long gap)
- {
- 	struct mm_struct *mm = vma->vm_mm;
- 	int error = 0;
-@@ -2208,12 +2209,6 @@ int expand_upwards(struct vm_area_struct
- 	if (!(vma->vm_flags & VM_GROWSUP))
- 		return -EFAULT;
- 
--	/* Guard against wrapping around to address 0. */
--	if (address < PAGE_ALIGN(address+4))
--		address = PAGE_ALIGN(address+4);
--	else
--		return -ENOMEM;
--
- 	/* We must make sure the anon_vma is allocated. */
- 	if (unlikely(anon_vma_prepare(vma)))
- 		return -ENOMEM;
-@@ -2234,7 +2229,7 @@ int expand_upwards(struct vm_area_struct
- 
- 		error = -ENOMEM;
- 		if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
--			error = acct_stack_growth(vma, size, grow);
-+			error = acct_stack_growth(vma, size, grow, gap);
- 			if (!error) {
- 				/*
- 				 * vma_gap_update() doesn't support concurrent
-@@ -2275,7 +2270,7 @@ int expand_upwards(struct vm_area_struct
-  * vma is the first one with address < vma->vm_start.  Have to extend vma.
-  */
- int expand_downwards(struct vm_area_struct *vma,
--				   unsigned long address)
-+				   unsigned long address, unsigned long gap)
- {
- 	struct mm_struct *mm = vma->vm_mm;
- 	int error;
-@@ -2305,7 +2300,7 @@ int expand_downwards(struct vm_area_stru
- 
- 		error = -ENOMEM;
- 		if (grow <= vma->vm_pgoff) {
--			error = acct_stack_growth(vma, size, grow);
-+			error = acct_stack_growth(vma, size, grow, gap);
- 			if (!error) {
- 				/*
- 				 * vma_gap_update() doesn't support concurrent
-@@ -2339,29 +2334,72 @@ int expand_downwards(struct vm_area_stru
- 	return error;
- }
- 
-+/* enforced gap between the expanding stack and other mappings. */
-+unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
-+
- /*
-  * Note how expand_stack() refuses to expand the stack all the way to
-  * abut the next virtual mapping, *unless* that mapping itself is also
-- * a stack mapping. We want to leave room for a guard page, after all
-+ * a stack mapping. We want to leave room for a guard area, after all
-  * (the guard page itself is not added here, that is done by the
-  * actual page faulting logic)
-- *
-- * This matches the behavior of the guard page logic (see mm/memory.c:
-- * check_stack_guard_page()), which only allows the guard page to be
-- * removed under these circumstances.
-  */
- #ifdef CONFIG_STACK_GROWSUP
-+unsigned long expandable_stack_area(struct vm_area_struct *vma,
-+		unsigned long address, unsigned long *gap)
-+{
-+	struct vm_area_struct *next = vma->vm_next;
-+	unsigned long guard_gap = stack_guard_gap;
-+	unsigned long guard_addr;
-+
-+	address = ALIGN(address, PAGE_SIZE);;
-+	if (!next)
-+		goto out;
-+
-+	if (next->vm_flags & VM_GROWSUP) {
-+		guard_gap = min(guard_gap, next->vm_start - address);
-+		goto out;
-+	}
-+
-+	if (next->vm_start - address < guard_gap)
-+		return -ENOMEM;
-+out:
-+	if (TASK_SIZE - address < guard_gap)
-+		guard_gap = TASK_SIZE - address;
-+	guard_addr = address + guard_gap;
-+	*gap = guard_gap;
-+
-+	return guard_addr;
-+}
-+
- int expand_stack(struct vm_area_struct *vma, unsigned long address)
- {
-+	unsigned long gap;
-+
-+	address = expandable_stack_area(vma, address, &gap);
-+	if (IS_ERR_VALUE(address))
-+		return -ENOMEM;
-+	return expand_upwards(vma, address, gap);
-+}
-+
-+int stack_guard_area(struct vm_area_struct *vma, unsigned long address)
-+{
- 	struct vm_area_struct *next;
- 
--	address &= PAGE_MASK;
-+	if (!(vma->vm_flags & VM_GROWSUP))
-+		return 0;
-+
-+	/*
-+	 * strictly speaking there is a guard gap between disjoint stacks
-+	 * but the gap is not canonical (it might be smaller) and it is
-+	 * reasonably safe to assume that we can ignore that gap for stack
-+	 * POPULATE or /proc/<pid>[s]maps purposes
-+	 */
- 	next = vma->vm_next;
--	if (next && next->vm_start == address + PAGE_SIZE) {
--		if (!(next->vm_flags & VM_GROWSUP))
--			return -ENOMEM;
--	}
--	return expand_upwards(vma, address);
-+	if (next && next->vm_flags & VM_GROWSUP)
-+		return 0;
-+
-+	return vma->vm_end - address <= stack_guard_gap;
- }
- 
- struct vm_area_struct *
-@@ -2380,17 +2418,73 @@ find_extend_vma(struct mm_struct *mm, un
- 	return prev;
- }
- #else
-+unsigned long expandable_stack_area(struct vm_area_struct *vma,
-+		unsigned long address, unsigned long *gap)
-+{
-+	struct vm_area_struct *prev = vma->vm_prev;
-+	unsigned long guard_gap = stack_guard_gap;
-+	unsigned long guard_addr;
-+
-+	address &= PAGE_MASK;
-+	if (!prev)
-+		goto out;
-+
-+	/*
-+	 * Is there a mapping abutting this one below?
-+	 *
-+	 * That's only ok if it's the same stack mapping
-+	 * that has gotten split or there is sufficient gap
-+	 * between mappings
-+	 */
-+	if (prev->vm_flags & VM_GROWSDOWN) {
-+		guard_gap = min(guard_gap, address - prev->vm_end);
-+		goto out;
-+	}
-+
-+	if (address - prev->vm_end < guard_gap)
-+		return -ENOMEM;
-+
-+out:
-+	/* make sure we won't underflow */
-+	if (address < mmap_min_addr)
-+		return -ENOMEM;
-+	if (address - mmap_min_addr < guard_gap)
-+		guard_gap = address - mmap_min_addr;
-+
-+	guard_addr = address - guard_gap;
-+	*gap = guard_gap;
-+
-+	return guard_addr;
-+}
-+
- int expand_stack(struct vm_area_struct *vma, unsigned long address)
- {
-+	unsigned long gap;
-+
-+	address = expandable_stack_area(vma, address, &gap);
-+	if (IS_ERR_VALUE(address))
-+		return -ENOMEM;
-+	return expand_downwards(vma, address, gap);
-+}
-+
-+int stack_guard_area(struct vm_area_struct *vma, unsigned long address)
-+{
- 	struct vm_area_struct *prev;
- 
--	address &= PAGE_MASK;
-+	if (!(vma->vm_flags & VM_GROWSDOWN))
-+		return 0;
-+
-+	/*
-+	 * strictly speaking there is a guard gap between disjoint stacks
-+	 * but the gap is not canonical (it might be smaller) and it is
-+	 * reasonably safe to assume that we can ignore that gap for stack
-+	 * POPULATE or /proc/<pid>[s]maps purposes
-+	 */
- 	prev = vma->vm_prev;
--	if (prev && prev->vm_end == address) {
--		if (!(prev->vm_flags & VM_GROWSDOWN))
--			return -ENOMEM;
--	}
--	return expand_downwards(vma, address);
-+	if (prev && prev->vm_flags & VM_GROWSDOWN)
-+		return 0;
-+
-+	return address - vma->vm_start < stack_guard_gap;
- }
- 
- struct vm_area_struct *
diff --git a/debian/patches/bugfix/all/mm-guard-against-under-sized-gap-in-unmapped_area-_topdown.patch b/debian/patches/bugfix/all/mm-guard-against-under-sized-gap-in-unmapped_area-_topdown.patch
new file mode 100644
index 0000000..5472fb5
--- /dev/null
+++ b/debian/patches/bugfix/all/mm-guard-against-under-sized-gap-in-unmapped_area-_topdown.patch
@@ -0,0 +1,27 @@
+Author: Hugh Dickins <hughd at google.com>
+Date: Mon, 19 Jun 2017 21:40:56 -0700
+Description: mm: Guard against under-sized gap in unmapped_area{,_topdown}()
+Origin: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1426125.html
+
+--- a/mm/mmap.c
++++ b/mm/mmap.c
+@@ -1817,7 +1817,8 @@ unsigned long unmapped_area(struct vm_un
+ 		/* Check if current node has a suitable gap */
+ 		if (gap_start > high_limit)
+ 			return -ENOMEM;
+-		if (gap_end >= low_limit && gap_end - gap_start >= length)
++		if (gap_end >= low_limit &&
++		    gap_end > gap_start && gap_end - gap_start >= length)
+ 			goto found;
+ 
+ 		/* Visit right subtree if it looks promising */
+@@ -1920,7 +1921,8 @@ unsigned long unmapped_area_topdown(stru
+ 		gap_end = vm_start_gap(vma);
+ 		if (gap_end < low_limit)
+ 			return -ENOMEM;
+-		if (gap_start <= high_limit && gap_end - gap_start >= length)
++		if (gap_start <= high_limit &&
++		    gap_end > gap_start && gap_end - gap_start >= length)
+ 			goto found;
+ 
+ 		/* Visit left subtree if it looks promising */
diff --git a/debian/patches/bugfix/all/mm-larger-stack-guard-gap-between-vmas.patch b/debian/patches/bugfix/all/mm-larger-stack-guard-gap-between-vmas.patch
new file mode 100644
index 0000000..546e544
--- /dev/null
+++ b/debian/patches/bugfix/all/mm-larger-stack-guard-gap-between-vmas.patch
@@ -0,0 +1,886 @@
+From: Hugh Dickins <hughd at google.com>
+Date: Mon, 19 Jun 2017 04:03:24 -0700
+Subject: mm: larger stack guard gap, between vmas
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-1000364
+
+commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream.
+
+Stack guard page is a useful feature to reduce a risk of stack smashing
+into a different mapping. We have been using a single page gap which
+is sufficient to prevent having stack adjacent to a different mapping.
+But this seems to be insufficient in the light of the stack usage in
+userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
+used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
+which is 256kB or stack strings with MAX_ARG_STRLEN.
+
+This will become especially dangerous for suid binaries and the default
+no limit for the stack size limit because those applications can be
+tricked to consume a large portion of the stack and a single glibc call
+could jump over the guard page. These attacks are not theoretical,
+unfortunatelly.
+
+Make those attacks less probable by increasing the stack guard gap
+to 1MB (on systems with 4k pages; but make it depend on the page size
+because systems with larger base pages might cap stack allocations in
+the PAGE_SIZE units) which should cover larger alloca() and VLA stack
+allocations. It is obviously not a full fix because the problem is
+somehow inherent, but it should reduce attack space a lot.
+
+One could argue that the gap size should be configurable from userspace,
+but that can be done later when somebody finds that the new 1MB is wrong
+for some special case applications.  For now, add a kernel command line
+option (stack_guard_gap) to specify the stack gap size (in page units).
+
+Implementation wise, first delete all the old code for stack guard page:
+because although we could get away with accounting one extra page in a
+stack vma, accounting a larger gap can break userspace - case in point,
+a program run with "ulimit -S -v 20000" failed when the 1MB gap was
+counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
+and strict non-overcommit mode.
+
+Instead of keeping gap inside the stack vma, maintain the stack guard
+gap as a gap between vmas: using vm_start_gap() in place of vm_start
+(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
+places which need to respect the gap - mainly arch_get_unmapped_area(),
+and and the vma tree's subtree_gap support for that.
+
+Original-patch-by: Oleg Nesterov <oleg at redhat.com>
+Original-patch-by: Michal Hocko <mhocko at suse.com>
+Signed-off-by: Hugh Dickins <hughd at google.com>
+Acked-by: Michal Hocko <mhocko at suse.com>
+Tested-by: Helge Deller <deller at gmx.de> # parisc
+Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
+[wt: backport to 4.11: adjust context]
+[wt: backport to 4.9: adjust context ; kernel doc was not in admin-guide]
+Signed-off-by: Willy Tarreau <w at 1wt.eu>
+Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
+---
+ Documentation/kernel-parameters.txt |    7 +
+ arch/arc/mm/mmap.c                  |    2 
+ arch/arm/mm/mmap.c                  |    4 
+ arch/frv/mm/elf-fdpic.c             |    2 
+ arch/mips/mm/mmap.c                 |    2 
+ arch/parisc/kernel/sys_parisc.c     |   15 ++-
+ arch/powerpc/mm/hugetlbpage-radix.c |    2 
+ arch/powerpc/mm/mmap.c              |    4 
+ arch/powerpc/mm/slice.c             |    2 
+ arch/s390/mm/mmap.c                 |    4 
+ arch/sh/mm/mmap.c                   |    4 
+ arch/sparc/kernel/sys_sparc_64.c    |    4 
+ arch/sparc/mm/hugetlbpage.c         |    2 
+ arch/tile/mm/hugetlbpage.c          |    2 
+ arch/x86/kernel/sys_x86_64.c        |    4 
+ arch/x86/mm/hugetlbpage.c           |    2 
+ arch/xtensa/kernel/syscall.c        |    2 
+ fs/hugetlbfs/inode.c                |    2 
+ fs/proc/task_mmu.c                  |    4 
+ include/linux/mm.h                  |   53 ++++++------
+ mm/gup.c                            |    5 -
+ mm/memory.c                         |   38 ---------
+ mm/mmap.c                           |  149 +++++++++++++++++++++---------------
+ 23 files changed, 152 insertions(+), 163 deletions(-)
+
+--- a/Documentation/kernel-parameters.txt
++++ b/Documentation/kernel-parameters.txt
+@@ -3932,6 +3932,13 @@ bytes respectively. Such letter suffixes
+ 	spia_pedr=
+ 	spia_peddr=
+ 
++	stack_guard_gap=	[MM]
++			override the default stack gap protection. The value
++			is in page units and it defines how many pages prior
++			to (for stacks growing down) resp. after (for stacks
++			growing up) the main stack are reserved for no other
++			mapping. Default value is 256 pages.
++
+ 	stacktrace	[FTRACE]
+ 			Enabled the stack tracer on boot up.
+ 
+--- a/arch/arc/mm/mmap.c
++++ b/arch/arc/mm/mmap.c
+@@ -64,7 +64,7 @@ arch_get_unmapped_area(struct file *filp
+ 
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+--- a/arch/arm/mm/mmap.c
++++ b/arch/arm/mm/mmap.c
+@@ -89,7 +89,7 @@ arch_get_unmapped_area(struct file *filp
+ 
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+@@ -140,7 +140,7 @@ arch_get_unmapped_area_topdown(struct fi
+ 			addr = PAGE_ALIGN(addr);
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-				(!vma || addr + len <= vma->vm_start))
++				(!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+--- a/arch/frv/mm/elf-fdpic.c
++++ b/arch/frv/mm/elf-fdpic.c
+@@ -74,7 +74,7 @@ unsigned long arch_get_unmapped_area(str
+ 		addr = PAGE_ALIGN(addr);
+ 		vma = find_vma(current->mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			goto success;
+ 	}
+ 
+--- a/arch/mips/mm/mmap.c
++++ b/arch/mips/mm/mmap.c
+@@ -92,7 +92,7 @@ static unsigned long arch_get_unmapped_a
+ 
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+--- a/arch/parisc/kernel/sys_parisc.c
++++ b/arch/parisc/kernel/sys_parisc.c
+@@ -88,7 +88,7 @@ unsigned long arch_get_unmapped_area(str
+ 		unsigned long len, unsigned long pgoff, unsigned long flags)
+ {
+ 	struct mm_struct *mm = current->mm;
+-	struct vm_area_struct *vma;
++	struct vm_area_struct *vma, *prev;
+ 	unsigned long task_size = TASK_SIZE;
+ 	int do_color_align, last_mmap;
+ 	struct vm_unmapped_area_info info;
+@@ -115,9 +115,10 @@ unsigned long arch_get_unmapped_area(str
+ 		else
+ 			addr = PAGE_ALIGN(addr);
+ 
+-		vma = find_vma(mm, addr);
++		vma = find_vma_prev(mm, addr, &prev);
+ 		if (task_size - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)) &&
++		    (!prev || addr >= vm_end_gap(prev)))
+ 			goto found_addr;
+ 	}
+ 
+@@ -141,7 +142,7 @@ arch_get_unmapped_area_topdown(struct fi
+ 			  const unsigned long len, const unsigned long pgoff,
+ 			  const unsigned long flags)
+ {
+-	struct vm_area_struct *vma;
++	struct vm_area_struct *vma, *prev;
+ 	struct mm_struct *mm = current->mm;
+ 	unsigned long addr = addr0;
+ 	int do_color_align, last_mmap;
+@@ -175,9 +176,11 @@ arch_get_unmapped_area_topdown(struct fi
+ 			addr = COLOR_ALIGN(addr, last_mmap, pgoff);
+ 		else
+ 			addr = PAGE_ALIGN(addr);
+-		vma = find_vma(mm, addr);
++
++		vma = find_vma_prev(mm, addr, &prev);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)) &&
++		    (!prev || addr >= vm_end_gap(prev)))
+ 			goto found_addr;
+ 	}
+ 
+--- a/arch/powerpc/mm/hugetlbpage-radix.c
++++ b/arch/powerpc/mm/hugetlbpage-radix.c
+@@ -65,7 +65,7 @@ radix__hugetlb_get_unmapped_area(struct
+ 		addr = ALIGN(addr, huge_page_size(h));
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 	/*
+--- a/arch/powerpc/mm/mmap.c
++++ b/arch/powerpc/mm/mmap.c
+@@ -106,7 +106,7 @@ radix__arch_get_unmapped_area(struct fil
+ 		addr = PAGE_ALIGN(addr);
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+@@ -142,7 +142,7 @@ radix__arch_get_unmapped_area_topdown(st
+ 		addr = PAGE_ALIGN(addr);
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+-				(!vma || addr + len <= vma->vm_start))
++				(!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+--- a/arch/powerpc/mm/slice.c
++++ b/arch/powerpc/mm/slice.c
+@@ -105,7 +105,7 @@ static int slice_area_is_free(struct mm_
+ 	if ((mm->task_size - len) < addr)
+ 		return 0;
+ 	vma = find_vma(mm, addr);
+-	return (!vma || (addr + len) <= vma->vm_start);
++	return (!vma || (addr + len) <= vm_start_gap(vma));
+ }
+ 
+ static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice)
+--- a/arch/s390/mm/mmap.c
++++ b/arch/s390/mm/mmap.c
+@@ -98,7 +98,7 @@ arch_get_unmapped_area(struct file *filp
+ 		addr = PAGE_ALIGN(addr);
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+@@ -136,7 +136,7 @@ arch_get_unmapped_area_topdown(struct fi
+ 		addr = PAGE_ALIGN(addr);
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+-				(!vma || addr + len <= vma->vm_start))
++				(!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+--- a/arch/sh/mm/mmap.c
++++ b/arch/sh/mm/mmap.c
+@@ -63,7 +63,7 @@ unsigned long arch_get_unmapped_area(str
+ 
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+@@ -113,7 +113,7 @@ arch_get_unmapped_area_topdown(struct fi
+ 
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+--- a/arch/sparc/kernel/sys_sparc_64.c
++++ b/arch/sparc/kernel/sys_sparc_64.c
+@@ -118,7 +118,7 @@ unsigned long arch_get_unmapped_area(str
+ 
+ 		vma = find_vma(mm, addr);
+ 		if (task_size - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+@@ -181,7 +181,7 @@ arch_get_unmapped_area_topdown(struct fi
+ 
+ 		vma = find_vma(mm, addr);
+ 		if (task_size - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+--- a/arch/sparc/mm/hugetlbpage.c
++++ b/arch/sparc/mm/hugetlbpage.c
+@@ -116,7 +116,7 @@ hugetlb_get_unmapped_area(struct file *f
+ 		addr = ALIGN(addr, HPAGE_SIZE);
+ 		vma = find_vma(mm, addr);
+ 		if (task_size - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 	if (mm->get_unmapped_area == arch_get_unmapped_area)
+--- a/arch/tile/mm/hugetlbpage.c
++++ b/arch/tile/mm/hugetlbpage.c
+@@ -232,7 +232,7 @@ unsigned long hugetlb_get_unmapped_area(
+ 		addr = ALIGN(addr, huge_page_size(h));
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 	if (current->mm->get_unmapped_area == arch_get_unmapped_area)
+--- a/arch/x86/kernel/sys_x86_64.c
++++ b/arch/x86/kernel/sys_x86_64.c
+@@ -140,7 +140,7 @@ arch_get_unmapped_area(struct file *filp
+ 		addr = PAGE_ALIGN(addr);
+ 		vma = find_vma(mm, addr);
+ 		if (end - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+@@ -183,7 +183,7 @@ arch_get_unmapped_area_topdown(struct fi
+ 		addr = PAGE_ALIGN(addr);
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-				(!vma || addr + len <= vma->vm_start))
++				(!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+--- a/arch/x86/mm/hugetlbpage.c
++++ b/arch/x86/mm/hugetlbpage.c
+@@ -144,7 +144,7 @@ hugetlb_get_unmapped_area(struct file *f
+ 		addr = ALIGN(addr, huge_page_size(h));
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 	if (mm->get_unmapped_area == arch_get_unmapped_area)
+--- a/arch/xtensa/kernel/syscall.c
++++ b/arch/xtensa/kernel/syscall.c
+@@ -87,7 +87,7 @@ unsigned long arch_get_unmapped_area(str
+ 		/* At this point:  (!vmm || addr < vmm->vm_end). */
+ 		if (TASK_SIZE - len < addr)
+ 			return -ENOMEM;
+-		if (!vmm || addr + len <= vmm->vm_start)
++		if (!vmm || addr + len <= vm_start_gap(vmm))
+ 			return addr;
+ 		addr = vmm->vm_end;
+ 		if (flags & MAP_SHARED)
+--- a/fs/hugetlbfs/inode.c
++++ b/fs/hugetlbfs/inode.c
+@@ -191,7 +191,7 @@ hugetlb_get_unmapped_area(struct file *f
+ 		addr = ALIGN(addr, huge_page_size(h));
+ 		vma = find_vma(mm, addr);
+ 		if (TASK_SIZE - len >= addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)))
+ 			return addr;
+ 	}
+ 
+--- a/fs/proc/task_mmu.c
++++ b/fs/proc/task_mmu.c
+@@ -299,11 +299,7 @@ show_map_vma(struct seq_file *m, struct
+ 
+ 	/* We don't show the stack guard page in /proc/maps */
+ 	start = vma->vm_start;
+-	if (stack_guard_page_start(vma, start))
+-		start += PAGE_SIZE;
+ 	end = vma->vm_end;
+-	if (stack_guard_page_end(vma, end))
+-		end -= PAGE_SIZE;
+ 
+ 	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
+ 	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
+--- a/include/linux/mm.h
++++ b/include/linux/mm.h
+@@ -1356,39 +1356,11 @@ int clear_page_dirty_for_io(struct page
+ 
+ int get_cmdline(struct task_struct *task, char *buffer, int buflen);
+ 
+-/* Is the vma a continuation of the stack vma above it? */
+-static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
+-{
+-	return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
+-}
+-
+ static inline bool vma_is_anonymous(struct vm_area_struct *vma)
+ {
+ 	return !vma->vm_ops;
+ }
+ 
+-static inline int stack_guard_page_start(struct vm_area_struct *vma,
+-					     unsigned long addr)
+-{
+-	return (vma->vm_flags & VM_GROWSDOWN) &&
+-		(vma->vm_start == addr) &&
+-		!vma_growsdown(vma->vm_prev, addr);
+-}
+-
+-/* Is the vma a continuation of the stack vma below it? */
+-static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
+-{
+-	return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
+-}
+-
+-static inline int stack_guard_page_end(struct vm_area_struct *vma,
+-					   unsigned long addr)
+-{
+-	return (vma->vm_flags & VM_GROWSUP) &&
+-		(vma->vm_end == addr) &&
+-		!vma_growsup(vma->vm_next, addr);
+-}
+-
+ int vma_is_stack_for_current(struct vm_area_struct *vma);
+ 
+ extern unsigned long move_page_tables(struct vm_area_struct *vma,
+@@ -2127,6 +2099,7 @@ void page_cache_async_readahead(struct a
+ 				pgoff_t offset,
+ 				unsigned long size);
+ 
++extern unsigned long stack_guard_gap;
+ /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
+ extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
+ 
+@@ -2155,6 +2128,30 @@ static inline struct vm_area_struct * fi
+ 	return vma;
+ }
+ 
++static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
++{
++	unsigned long vm_start = vma->vm_start;
++
++	if (vma->vm_flags & VM_GROWSDOWN) {
++		vm_start -= stack_guard_gap;
++		if (vm_start > vma->vm_start)
++			vm_start = 0;
++	}
++	return vm_start;
++}
++
++static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
++{
++	unsigned long vm_end = vma->vm_end;
++
++	if (vma->vm_flags & VM_GROWSUP) {
++		vm_end += stack_guard_gap;
++		if (vm_end < vma->vm_end)
++			vm_end = -PAGE_SIZE;
++	}
++	return vm_end;
++}
++
+ static inline unsigned long vma_pages(struct vm_area_struct *vma)
+ {
+ 	return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+--- a/mm/gup.c
++++ b/mm/gup.c
+@@ -370,11 +370,6 @@ static int faultin_page(struct task_stru
+ 	/* mlock all present pages, but do not fault in new pages */
+ 	if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
+ 		return -ENOENT;
+-	/* For mm_populate(), just skip the stack guard page. */
+-	if ((*flags & FOLL_POPULATE) &&
+-			(stack_guard_page_start(vma, address) ||
+-			 stack_guard_page_end(vma, address + PAGE_SIZE)))
+-		return -ENOENT;
+ 	if (*flags & FOLL_WRITE)
+ 		fault_flags |= FAULT_FLAG_WRITE;
+ 	if (*flags & FOLL_REMOTE)
+--- a/mm/memory.c
++++ b/mm/memory.c
+@@ -2699,40 +2699,6 @@ out_release:
+ }
+ 
+ /*
+- * This is like a special single-page "expand_{down|up}wards()",
+- * except we must first make sure that 'address{-|+}PAGE_SIZE'
+- * doesn't hit another vma.
+- */
+-static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
+-{
+-	address &= PAGE_MASK;
+-	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
+-		struct vm_area_struct *prev = vma->vm_prev;
+-
+-		/*
+-		 * Is there a mapping abutting this one below?
+-		 *
+-		 * That's only ok if it's the same stack mapping
+-		 * that has gotten split..
+-		 */
+-		if (prev && prev->vm_end == address)
+-			return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
+-
+-		return expand_downwards(vma, address - PAGE_SIZE);
+-	}
+-	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
+-		struct vm_area_struct *next = vma->vm_next;
+-
+-		/* As VM_GROWSDOWN but s/below/above/ */
+-		if (next && next->vm_start == address + PAGE_SIZE)
+-			return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
+-
+-		return expand_upwards(vma, address + PAGE_SIZE);
+-	}
+-	return 0;
+-}
+-
+-/*
+  * We enter with non-exclusive mmap_sem (to exclude vma changes,
+  * but allow concurrent faults), and pte mapped but not yet locked.
+  * We return with mmap_sem still held, but pte unmapped and unlocked.
+@@ -2748,10 +2714,6 @@ static int do_anonymous_page(struct faul
+ 	if (vma->vm_flags & VM_SHARED)
+ 		return VM_FAULT_SIGBUS;
+ 
+-	/* Check if we need to add a guard page to the stack */
+-	if (check_stack_guard_page(vma, fe->address) < 0)
+-		return VM_FAULT_SIGSEGV;
+-
+ 	/*
+ 	 * Use pte_alloc() instead of pte_alloc_map().  We can't run
+ 	 * pte_offset_map() on pmds where a huge pmd might be created
+--- a/mm/mmap.c
++++ b/mm/mmap.c
+@@ -183,6 +183,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
+ 	unsigned long retval;
+ 	unsigned long newbrk, oldbrk;
+ 	struct mm_struct *mm = current->mm;
++	struct vm_area_struct *next;
+ 	unsigned long min_brk;
+ 	bool populate;
+ 
+@@ -228,7 +229,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
+ 	}
+ 
+ 	/* Check against existing mmap mappings. */
+-	if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
++	next = find_vma(mm, oldbrk);
++	if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
+ 		goto out;
+ 
+ 	/* Ok, looks good - let it rip. */
+@@ -251,10 +253,22 @@ out:
+ 
+ static long vma_compute_subtree_gap(struct vm_area_struct *vma)
+ {
+-	unsigned long max, subtree_gap;
+-	max = vma->vm_start;
+-	if (vma->vm_prev)
+-		max -= vma->vm_prev->vm_end;
++	unsigned long max, prev_end, subtree_gap;
++
++	/*
++	 * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
++	 * allow two stack_guard_gaps between them here, and when choosing
++	 * an unmapped area; whereas when expanding we only require one.
++	 * That's a little inconsistent, but keeps the code here simpler.
++	 */
++	max = vm_start_gap(vma);
++	if (vma->vm_prev) {
++		prev_end = vm_end_gap(vma->vm_prev);
++		if (max > prev_end)
++			max -= prev_end;
++		else
++			max = 0;
++	}
+ 	if (vma->vm_rb.rb_left) {
+ 		subtree_gap = rb_entry(vma->vm_rb.rb_left,
+ 				struct vm_area_struct, vm_rb)->rb_subtree_gap;
+@@ -350,7 +364,7 @@ static void validate_mm(struct mm_struct
+ 			anon_vma_unlock_read(anon_vma);
+ 		}
+ 
+-		highest_address = vma->vm_end;
++		highest_address = vm_end_gap(vma);
+ 		vma = vma->vm_next;
+ 		i++;
+ 	}
+@@ -539,7 +553,7 @@ void __vma_link_rb(struct mm_struct *mm,
+ 	if (vma->vm_next)
+ 		vma_gap_update(vma->vm_next);
+ 	else
+-		mm->highest_vm_end = vma->vm_end;
++		mm->highest_vm_end = vm_end_gap(vma);
+ 
+ 	/*
+ 	 * vma->vm_prev wasn't known when we followed the rbtree to find the
+@@ -854,7 +868,7 @@ again:
+ 			vma_gap_update(vma);
+ 		if (end_changed) {
+ 			if (!next)
+-				mm->highest_vm_end = end;
++				mm->highest_vm_end = vm_end_gap(vma);
+ 			else if (!adjust_next)
+ 				vma_gap_update(next);
+ 		}
+@@ -939,7 +953,7 @@ again:
+ 			 * mm->highest_vm_end doesn't need any update
+ 			 * in remove_next == 1 case.
+ 			 */
+-			VM_WARN_ON(mm->highest_vm_end != end);
++			VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
+ 		}
+ 	}
+ 	if (insert && file)
+@@ -1783,7 +1797,7 @@ unsigned long unmapped_area(struct vm_un
+ 
+ 	while (true) {
+ 		/* Visit left subtree if it looks promising */
+-		gap_end = vma->vm_start;
++		gap_end = vm_start_gap(vma);
+ 		if (gap_end >= low_limit && vma->vm_rb.rb_left) {
+ 			struct vm_area_struct *left =
+ 				rb_entry(vma->vm_rb.rb_left,
+@@ -1794,7 +1808,7 @@ unsigned long unmapped_area(struct vm_un
+ 			}
+ 		}
+ 
+-		gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
++		gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
+ check_current:
+ 		/* Check if current node has a suitable gap */
+ 		if (gap_start > high_limit)
+@@ -1821,8 +1835,8 @@ check_current:
+ 			vma = rb_entry(rb_parent(prev),
+ 				       struct vm_area_struct, vm_rb);
+ 			if (prev == vma->vm_rb.rb_left) {
+-				gap_start = vma->vm_prev->vm_end;
+-				gap_end = vma->vm_start;
++				gap_start = vm_end_gap(vma->vm_prev);
++				gap_end = vm_start_gap(vma);
+ 				goto check_current;
+ 			}
+ 		}
+@@ -1886,7 +1900,7 @@ unsigned long unmapped_area_topdown(stru
+ 
+ 	while (true) {
+ 		/* Visit right subtree if it looks promising */
+-		gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
++		gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
+ 		if (gap_start <= high_limit && vma->vm_rb.rb_right) {
+ 			struct vm_area_struct *right =
+ 				rb_entry(vma->vm_rb.rb_right,
+@@ -1899,7 +1913,7 @@ unsigned long unmapped_area_topdown(stru
+ 
+ check_current:
+ 		/* Check if current node has a suitable gap */
+-		gap_end = vma->vm_start;
++		gap_end = vm_start_gap(vma);
+ 		if (gap_end < low_limit)
+ 			return -ENOMEM;
+ 		if (gap_start <= high_limit && gap_end - gap_start >= length)
+@@ -1925,7 +1939,7 @@ check_current:
+ 				       struct vm_area_struct, vm_rb);
+ 			if (prev == vma->vm_rb.rb_right) {
+ 				gap_start = vma->vm_prev ?
+-					vma->vm_prev->vm_end : 0;
++					vm_end_gap(vma->vm_prev) : 0;
+ 				goto check_current;
+ 			}
+ 		}
+@@ -1963,7 +1977,7 @@ arch_get_unmapped_area(struct file *filp
+ 		unsigned long len, unsigned long pgoff, unsigned long flags)
+ {
+ 	struct mm_struct *mm = current->mm;
+-	struct vm_area_struct *vma;
++	struct vm_area_struct *vma, *prev;
+ 	struct vm_unmapped_area_info info;
+ 
+ 	if (len > TASK_SIZE - mmap_min_addr)
+@@ -1974,9 +1988,10 @@ arch_get_unmapped_area(struct file *filp
+ 
+ 	if (addr) {
+ 		addr = PAGE_ALIGN(addr);
+-		vma = find_vma(mm, addr);
++		vma = find_vma_prev(mm, addr, &prev);
+ 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+-		    (!vma || addr + len <= vma->vm_start))
++		    (!vma || addr + len <= vm_start_gap(vma)) &&
++		    (!prev || addr >= vm_end_gap(prev)))
+ 			return addr;
+ 	}
+ 
+@@ -1999,7 +2014,7 @@ arch_get_unmapped_area_topdown(struct fi
+ 			  const unsigned long len, const unsigned long pgoff,
+ 			  const unsigned long flags)
+ {
+-	struct vm_area_struct *vma;
++	struct vm_area_struct *vma, *prev;
+ 	struct mm_struct *mm = current->mm;
+ 	unsigned long addr = addr0;
+ 	struct vm_unmapped_area_info info;
+@@ -2014,9 +2029,10 @@ arch_get_unmapped_area_topdown(struct fi
+ 	/* requesting a specific address */
+ 	if (addr) {
+ 		addr = PAGE_ALIGN(addr);
+-		vma = find_vma(mm, addr);
++		vma = find_vma_prev(mm, addr, &prev);
+ 		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+-				(!vma || addr + len <= vma->vm_start))
++				(!vma || addr + len <= vm_start_gap(vma)) &&
++				(!prev || addr >= vm_end_gap(prev)))
+ 			return addr;
+ 	}
+ 
+@@ -2151,21 +2167,19 @@ find_vma_prev(struct mm_struct *mm, unsi
+  * update accounting. This is shared with both the
+  * grow-up and grow-down cases.
+  */
+-static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
++static int acct_stack_growth(struct vm_area_struct *vma,
++			     unsigned long size, unsigned long grow)
+ {
+ 	struct mm_struct *mm = vma->vm_mm;
+ 	struct rlimit *rlim = current->signal->rlim;
+-	unsigned long new_start, actual_size;
++	unsigned long new_start;
+ 
+ 	/* address space limit tests */
+ 	if (!may_expand_vm(mm, vma->vm_flags, grow))
+ 		return -ENOMEM;
+ 
+ 	/* Stack limit test */
+-	actual_size = size;
+-	if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
+-		actual_size -= PAGE_SIZE;
+-	if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
++	if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
+ 		return -ENOMEM;
+ 
+ 	/* mlock limit tests */
+@@ -2203,17 +2217,30 @@ static int acct_stack_growth(struct vm_a
+ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
+ {
+ 	struct mm_struct *mm = vma->vm_mm;
++	struct vm_area_struct *next;
++	unsigned long gap_addr;
+ 	int error = 0;
+ 
+ 	if (!(vma->vm_flags & VM_GROWSUP))
+ 		return -EFAULT;
+ 
+ 	/* Guard against wrapping around to address 0. */
+-	if (address < PAGE_ALIGN(address+4))
+-		address = PAGE_ALIGN(address+4);
+-	else
++	address &= PAGE_MASK;
++	address += PAGE_SIZE;
++	if (!address)
+ 		return -ENOMEM;
+ 
++	/* Enforce stack_guard_gap */
++	gap_addr = address + stack_guard_gap;
++	if (gap_addr < address)
++		return -ENOMEM;
++	next = vma->vm_next;
++	if (next && next->vm_start < gap_addr) {
++		if (!(next->vm_flags & VM_GROWSUP))
++			return -ENOMEM;
++		/* Check that both stack segments have the same anon_vma? */
++	}
++
+ 	/* We must make sure the anon_vma is allocated. */
+ 	if (unlikely(anon_vma_prepare(vma)))
+ 		return -ENOMEM;
+@@ -2257,7 +2284,7 @@ int expand_upwards(struct vm_area_struct
+ 				if (vma->vm_next)
+ 					vma_gap_update(vma->vm_next);
+ 				else
+-					mm->highest_vm_end = address;
++					mm->highest_vm_end = vm_end_gap(vma);
+ 				spin_unlock(&mm->page_table_lock);
+ 
+ 				perf_event_mmap(vma);
+@@ -2278,6 +2305,8 @@ int expand_downwards(struct vm_area_stru
+ 				   unsigned long address)
+ {
+ 	struct mm_struct *mm = vma->vm_mm;
++	struct vm_area_struct *prev;
++	unsigned long gap_addr;
+ 	int error;
+ 
+ 	address &= PAGE_MASK;
+@@ -2285,6 +2314,17 @@ int expand_downwards(struct vm_area_stru
+ 	if (error)
+ 		return error;
+ 
++	/* Enforce stack_guard_gap */
++	gap_addr = address - stack_guard_gap;
++	if (gap_addr > address)
++		return -ENOMEM;
++	prev = vma->vm_prev;
++	if (prev && prev->vm_end > gap_addr) {
++		if (!(prev->vm_flags & VM_GROWSDOWN))
++			return -ENOMEM;
++		/* Check that both stack segments have the same anon_vma? */
++	}
++
+ 	/* We must make sure the anon_vma is allocated. */
+ 	if (unlikely(anon_vma_prepare(vma)))
+ 		return -ENOMEM;
+@@ -2339,28 +2379,25 @@ int expand_downwards(struct vm_area_stru
+ 	return error;
+ }
+ 
+-/*
+- * Note how expand_stack() refuses to expand the stack all the way to
+- * abut the next virtual mapping, *unless* that mapping itself is also
+- * a stack mapping. We want to leave room for a guard page, after all
+- * (the guard page itself is not added here, that is done by the
+- * actual page faulting logic)
+- *
+- * This matches the behavior of the guard page logic (see mm/memory.c:
+- * check_stack_guard_page()), which only allows the guard page to be
+- * removed under these circumstances.
+- */
++/* enforced gap between the expanding stack and other mappings. */
++unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
++
++static int __init cmdline_parse_stack_guard_gap(char *p)
++{
++	unsigned long val;
++	char *endptr;
++
++	val = simple_strtoul(p, &endptr, 10);
++	if (!*endptr)
++		stack_guard_gap = val << PAGE_SHIFT;
++
++	return 0;
++}
++__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
++
+ #ifdef CONFIG_STACK_GROWSUP
+ int expand_stack(struct vm_area_struct *vma, unsigned long address)
+ {
+-	struct vm_area_struct *next;
+-
+-	address &= PAGE_MASK;
+-	next = vma->vm_next;
+-	if (next && next->vm_start == address + PAGE_SIZE) {
+-		if (!(next->vm_flags & VM_GROWSUP))
+-			return -ENOMEM;
+-	}
+ 	return expand_upwards(vma, address);
+ }
+ 
+@@ -2382,14 +2419,6 @@ find_extend_vma(struct mm_struct *mm, un
+ #else
+ int expand_stack(struct vm_area_struct *vma, unsigned long address)
+ {
+-	struct vm_area_struct *prev;
+-
+-	address &= PAGE_MASK;
+-	prev = vma->vm_prev;
+-	if (prev && prev->vm_end == address) {
+-		if (!(prev->vm_flags & VM_GROWSDOWN))
+-			return -ENOMEM;
+-	}
+ 	return expand_downwards(vma, address);
+ }
+ 
+@@ -2487,7 +2516,7 @@ detach_vmas_to_be_unmapped(struct mm_str
+ 		vma->vm_prev = prev;
+ 		vma_gap_update(vma);
+ 	} else
+-		mm->highest_vm_end = prev ? prev->vm_end : 0;
++		mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
+ 	tail_vma->vm_next = NULL;
+ 
+ 	/* Kill the cache */
diff --git a/debian/patches/bugfix/all/mm-proc-cap-the-stack-gap-for-unpopulated-growing-vm.patch b/debian/patches/bugfix/all/mm-proc-cap-the-stack-gap-for-unpopulated-growing-vm.patch
deleted file mode 100644
index 1d187b1..0000000
--- a/debian/patches/bugfix/all/mm-proc-cap-the-stack-gap-for-unpopulated-growing-vm.patch
+++ /dev/null
@@ -1,45 +0,0 @@
-From: Michal Hocko <mhocko at suse.com>
-Date: Wed, 14 Jun 2017 08:17:15 +0200
-Subject: mm, proc: cap the stack gap for unpopulated growing vmas
-Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-1000364
-
-Oleg has noticed that show_map_vma has been overly eager to cut the
-the vma range for growing VMAs. This wasn't a big deal with 4kB stack
-gap but now that the gap is much larger we can simply get a bogus VMA
-range in show_map_vma.
-To quote Oleg
-: On ppc PAGE_SIZE == 64K, so stack_guard_gap == 16M, the application does
-: mmap(..., length=4M, ... MAP_GROWSDOWN) and /proc/pid/maps happily reports
-:
-:       30001000000-30000400000 rw-p 00000000 00:00 0
-
-Let's cap the reported range and show an empty range for this peculiar
-case which is what we have been doing for a long time.  Note that the
-range will expand as soon as the first page fault happens on this range.
-
-Reported-by: Jan Stancek <jstancek at redhat.com>
-Signed-off-by: Michal Hocko <mhocko at suse.com>
----
- fs/proc/task_mmu.c | 4 ++--
- 1 file changed, 2 insertions(+), 2 deletions(-)
-
-diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
-index 5ef3e14d235f..6f38f96d725f 100644
---- a/fs/proc/task_mmu.c
-+++ b/fs/proc/task_mmu.c
-@@ -303,10 +303,10 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
- 	end = vma->vm_end;
- 	if (vma->vm_flags & VM_GROWSDOWN) {
- 		if (stack_guard_area(vma, start))
--			start += stack_guard_gap;
-+			start = min(end, start + stack_guard_gap);
- 	} else if (vma->vm_flags & VM_GROWSUP) {
- 		if (stack_guard_area(vma, end))
--			end -= stack_guard_gap;
-+			end = max(start, end - stack_guard_gap);
- 	}
- 
- 	seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
--- 
-2.11.0
-
diff --git a/debian/patches/bugfix/all/mm-proc-drop-priv-parameter-from-is_stack.patch b/debian/patches/bugfix/all/mm-proc-drop-priv-parameter-from-is_stack.patch
deleted file mode 100644
index bdb1cf6..0000000
--- a/debian/patches/bugfix/all/mm-proc-drop-priv-parameter-from-is_stack.patch
+++ /dev/null
@@ -1,89 +0,0 @@
-From: Michal Hocko <mhocko at suse.com>
-Date: Wed, 14 Jun 2017 08:17:20 +0200
-Subject: mm, proc: drop priv parameter from is_stack
-Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-1000364
-
-We do not really need priv parameter since b18cb64ead40 ("fs/proc: Stop
-trying to report thread stacks") simplified is_stack.
-
-Signed-off-by: Michal Hocko <mhocko at suse.com>
----
- fs/proc/task_mmu.c   | 10 ++++------
- fs/proc/task_nommu.c |  5 ++---
- 2 files changed, 6 insertions(+), 9 deletions(-)
-
-diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
-index 6f38f96d725f..f05faa18d8b6 100644
---- a/fs/proc/task_mmu.c
-+++ b/fs/proc/task_mmu.c
-@@ -266,8 +266,7 @@ static int do_maps_open(struct inode *inode, struct file *file,
-  * Indicate if the VMA is a stack for the given task; for
-  * /proc/PID/maps that is the stack of the main task.
-  */
--static int is_stack(struct proc_maps_private *priv,
--		    struct vm_area_struct *vma)
-+static int is_stack(struct vm_area_struct *vma)
- {
- 	/*
- 	 * We make no effort to guess what a given thread considers to be
-@@ -283,7 +282,6 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
- {
- 	struct mm_struct *mm = vma->vm_mm;
- 	struct file *file = vma->vm_file;
--	struct proc_maps_private *priv = m->private;
- 	vm_flags_t flags = vma->vm_flags;
- 	unsigned long ino = 0;
- 	unsigned long long pgoff = 0;
-@@ -349,7 +347,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
- 			goto done;
- 		}
- 
--		if (is_stack(priv, vma))
-+		if (is_stack(vma))
- 			name = "[stack]";
- 	}
- 
-@@ -809,7 +807,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
- 		   (vma->vm_flags & VM_LOCKED) ?
- 			(unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);
- 
--	if (is_stack(m->private, vma))
-+	if (is_stack(vma))
- 		seq_printf(m, "Stack_Gap:      %8lu kB\n", stack_guard_gap >>10);
- 
- 	arch_show_smap(m, vma);
-@@ -1681,7 +1679,7 @@ static int show_numa_map(struct seq_file *m, void *v, int is_pid)
- 		seq_file_path(m, file, "\n\t= ");
- 	} else if (vma->vm_start <= mm->brk && vma->vm_end >= mm->start_brk) {
- 		seq_puts(m, " heap");
--	} else if (is_stack(proc_priv, vma)) {
-+	} else if (is_stack(vma)) {
- 		seq_puts(m, " stack");
- 	}
- 
-diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
-index 23266694db11..dea90b566a6e 100644
---- a/fs/proc/task_nommu.c
-+++ b/fs/proc/task_nommu.c
-@@ -125,8 +125,7 @@ unsigned long task_statm(struct mm_struct *mm,
- 	return size;
- }
- 
--static int is_stack(struct proc_maps_private *priv,
--		    struct vm_area_struct *vma)
-+static int is_stack(struct vm_area_struct *vma)
- {
- 	struct mm_struct *mm = vma->vm_mm;
- 
-@@ -178,7 +177,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
- 	if (file) {
- 		seq_pad(m, ' ');
- 		seq_file_path(m, file, "");
--	} else if (mm && is_stack(priv, vma)) {
-+	} else if (mm && is_stack(vma)) {
- 		seq_pad(m, ' ');
- 		seq_printf(m, "[stack]");
- 	}
--- 
-2.11.0
-
diff --git a/debian/patches/series b/debian/patches/series
index 4eb9297..e652463 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -120,12 +120,8 @@ bugfix/all/sctp-do-not-inherit-ipv6_-mc-ac-fl-_list-from-parent.patch
 bugfix/all/ipv6-dccp-do-not-inherit-ipv6_mc_list-from-parent.patch
 bugfix/all/crypto-skcipher-Add-missing-api-setkey-checks.patch
 bugfix/all/ipv6-fix-out-of-bound-writes-in-__ip6_append_data.patch
-bugfix/all/mm-enlarge-stack-guard-gap.patch
-bugfix/all/mm-allow-to-configure-stack-gap-size.patch
-bugfix/all/mm-proc-cap-the-stack-gap-for-unpopulated-growing-vm.patch
-bugfix/all/mm-proc-drop-priv-parameter-from-is_stack.patch
-bugfix/all/mm-do-not-collapse-stack-gap-into-THP.patch
-bugfix/all/fold-me-mm-allow-to-configure-stack-gap-size.patch
+bugfix/all/mm-larger-stack-guard-gap-between-vmas.patch
+bugfix/all/mm-guard-against-under-sized-gap-in-unmapped_area-_topdown.patch
 
 # Fix exported symbol versions
 bugfix/ia64/revert-ia64-move-exports-to-definitions.patch

-- 
Alioth's /usr/local/bin/git-commit-notice on /srv/git.debian.org/git/kernel/linux.git



More information about the Kernel-svn-changes mailing list