Messages in this thread Patch in this message | | | From | Paul Gortmaker <> | Subject | [v2.6.34-stable 004/165] vm: fix vm_pgoff wrap in stack expansion | Date | Wed, 15 Aug 2012 15:45:48 -0400 |
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From: Linus Torvalds <torvalds@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 <robert@swiecki.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [PG: .34 doesn't have perf call via 3af9e859 (in .36); adjust accordingly] Signed-off-by: Paul Gortmaker <paul.gortmaker@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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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