From: Linus Torvalds <torva...@linux-foundation.org>
-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------
commit a626ca6a656450e9f4df91d0dda238fff23285f4 upstream.
Commit 982134ba6261 ("mm: avoid wrapping vm_pgoff in mremap()") fixed
the case of a expanding mapping causing vm_pgoff wrapping when you used
mremap. But there was another case where we expand mappings hiding in
plain sight: the automatic stack expansion.
This fixes that case too.
This one also found by Robert Święcki, using his nasty system call
fuzzer tool. Good job.
Reported-and-tested-by: Robert Święcki <rob...@swiecki.net>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
[PG: .34 doesn't have perf call via 3af9e859 (in .36); adjust accordingly]
Signed-off-by: Paul Gortmaker <paul.gortma...@windriver.com>
---
mm/mmap.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index b42b469..fe9b76a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1784,10 +1784,13 @@ static int expand_downwards(struct vm_area_struct *vma,
size = vma->vm_end - address;
grow = (vma->vm_start - address) >> PAGE_SHIFT;
- error = acct_stack_growth(vma, size, grow);
- if (!error) {
- vma->vm_start = address;
- vma->vm_pgoff -= grow;
+ error = -ENOMEM;
+ if (grow <= vma->vm_pgoff) {
+ error = acct_stack_growth(vma, size, grow);
+ if (!error) {
+ vma->vm_start = address;
+ vma->vm_pgoff -= grow;
+ }
}
}
anon_vma_unlock(vma);
--
1.7.12.rc2
--
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