Patchwork [2/2] vm: fix vm_pgoff wrap in upward expansion - CVE-2011-2496

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Submitter Paolo Pisati
Date Oct. 12, 2011, 10:03 a.m.
Message ID <1318413796-4617-1-git-send-email-paolo.pisati@canonical.com>
Download mbox | patch
Permalink /patch/119177/
State New
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Comments

Paolo Pisati - Oct. 12, 2011, 10:03 a.m.
From: Hugh Dickins <hughd@google.com>

Commit a626ca6a6564 ("vm: fix vm_pgoff wrap in stack expansion") fixed
the case of an expanding mapping causing vm_pgoff wrapping when you had
downward stack expansion.  But there was another case where IA64 and
PA-RISC expand mappings: upward expansion.

This fixes that case too.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

CVE-2011-2496

BugLink: http://bugs.launchpad.net/bugs/869243

commit upstream 42c36f63ac1366ab0ecc2d5717821362c259f517

Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
---
 mm/mmap.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)
Andy Whitcroft - Oct. 12, 2011, 10:45 a.m.
On Wed, Oct 12, 2011 at 12:03:16PM +0200, Paolo Pisati wrote:

> commit upstream 42c36f63ac1366ab0ecc2d5717821362c259f517
> 
> Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

It is helpful later to know if this was a backport or a cherry-pick, so
we tend to recommend either:

(backported from commit xxx)

or:

(cherry-picked from commit xxx)

depending which it was.

-apw

Patch

diff --git a/mm/mmap.c b/mm/mmap.c
index 6aa3f80..a8bde69 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1737,9 +1737,12 @@  int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 		size = address - vma->vm_start;
 		grow = (address - vma->vm_end) >> PAGE_SHIFT;
 
-		error = acct_stack_growth(vma, size, grow);
-		if (!error)
-			vma->vm_end = address;
+		error = -ENOMEM;
+		if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
+			error = acct_stack_growth(vma, size, grow);
+			if (!error)
+				vma->vm_end = address;
+		}
 	}
 	anon_vma_unlock(vma);
 	return error;