[linux] 05/06: fold me "mm: allow to configure stack gap size"

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carnil pushed a commit to branch jessie-security
in repository linux.

commit 12c973540618e5985eeddb392aa5908d630a3d84
Author: Salvatore Bonaccorso <carnil at debian.org>
Date:   Fri Jun 16 13:15:55 2017 +0200

    fold me "mm: allow to configure stack gap size"
---
 debian/changelog                                   |  1 +
 ...d-me-mm-allow-to-configure-stack-gap-size.patch | 79 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 3 files changed, 81 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index 9c8c51e..f719c2f 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -26,6 +26,7 @@ linux (3.16.43-2+deb8u1) UNRELEASED; urgency=medium
   * mm: allow to configure stack gap size
   * mm, proc: cap the stack gap for unpopulated growing vmas
   * mm: do not collapse stack gap into THP
+  * fold me "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/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
new file mode 100644
index 0000000..6447d59
--- /dev/null
+++ b/debian/patches/bugfix/all/fold-me-mm-allow-to-configure-stack-gap-size.patch
@@ -0,0 +1,79 @@
+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
+[carnil: backport for 3.16, adjust context, use of vm_is_stack in 3.16 rather
+is_stack]
+---
+ fs/proc/task_mmu.c | 19 +++++++++++++------
+ 1 file changed, 13 insertions(+), 6 deletions(-)
+
+--- a/fs/proc/task_mmu.c
++++ b/fs/proc/task_mmu.c
+@@ -251,7 +251,7 @@ static int do_maps_open(struct inode *in
+ }
+ 
+ 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;
+@@ -278,11 +278,17 @@ show_map_vma(struct seq_file *m, struct
+ 	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);
+@@ -359,7 +365,7 @@ static int show_map(struct seq_file *m,
+ 	struct proc_maps_private *priv = m->private;
+ 	struct task_struct *task = priv->task;
+ 
+-	show_map_vma(m, vma, is_pid);
++	show_map_vma(m, vma, is_pid, NULL);
+ 
+ 	if (m->count < m->size)  /* vma is copied successfully */
+ 		m->version = (vma != get_gate_vma(task->mm))
+@@ -598,6 +604,7 @@ static int show_smap(struct seq_file *m,
+ 		.mm = vma->vm_mm,
+ 		.private = &mss,
+ 	};
++	bool has_gap = false;
+ 
+ 	memset(&mss, 0, sizeof mss);
+ 	mss.vma = vma;
+@@ -605,7 +612,7 @@ static int show_smap(struct seq_file *m,
+ 	if (vma->vm_mm && !is_vm_hugetlb_page(vma))
+ 		walk_page_range(vma->vm_start, vma->vm_end, &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"
+@@ -642,7 +649,7 @@ 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))
++	if (has_gap)
+ 		seq_printf(m, "Stack_Gap:      %8lu kB\n", stack_guard_gap >>10);
+ 
+ 	show_smap_vma_flags(m, vma);
diff --git a/debian/patches/series b/debian/patches/series
index 74d634b..7733634 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -714,6 +714,7 @@ 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-do-not-collapse-stack-gap-into-THP.patch
+bugfix/all/fold-me-mm-allow-to-configure-stack-gap-size.patch
 
 # Fix ABI changes
 debian/of-fix-abi-changes.patch

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