[linux] 02/06: mm: allow to configure stack gap size
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Mon Jun 19 15:38:07 UTC 2017
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carnil pushed a commit to branch jessie-security
in repository linux.
commit 76d0367ab38f1b3c3844560420cc1f1adb5a41dd
Author: Salvatore Bonaccorso <carnil at debian.org>
Date: Fri Jun 16 10:57:00 2017 +0200
mm: allow to configure stack gap size
---
debian/changelog | 1 +
.../all/mm-allow-to-configure-stack-gap-size.patch | 71 ++++++++++++++++++++++
debian/patches/series | 1 +
3 files changed, 73 insertions(+)
diff --git a/debian/changelog b/debian/changelog
index 2f77d08..c26a946 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -23,6 +23,7 @@ linux (3.16.43-2+deb8u1) UNRELEASED; urgency=medium
[ Salvatore Bonaccorso ]
* mm: enlarge stack guard gap (CVE-2017-1000364)
+ * mm: allow to configure stack gap size
-- Ben Hutchings <ben at decadent.org.uk> Wed, 31 May 2017 11:52:42 +0100
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
new file mode 100644
index 0000000..c516800
--- /dev/null
+++ b/debian/patches/bugfix/all/mm-allow-to-configure-stack-gap-size.patch
@@ -0,0 +1,71 @@
+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 3.16
+ - context adjustment
+ - adjust location for documentation
+ - is_stack -> vm_is_stack]
+---
+ 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
+@@ -3150,6 +3150,13 @@ 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
+@@ -642,6 +642,9 @@ static int show_smap(struct seq_file *m,
+ seq_printf(m, "Nonlinear: %8lu kB\n",
+ mss.nonlinear >> 10);
+
++ if (vm_is_stack(m->private, vma, is_pid))
++ seq_printf(m, "Stack_Gap: %8lu kB\n", stack_guard_gap >>10);
++
+ show_smap_vma_flags(m, vma);
+
+ if (m->count < m->size) /* vma is copied successfully */
+--- a/mm/mmap.c
++++ b/mm/mmap.c
+@@ -2261,6 +2261,19 @@ 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/series b/debian/patches/series
index 2082352..172a92f 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -711,6 +711,7 @@ 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/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
# Fix ABI changes
debian/of-fix-abi-changes.patch
--
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