Messages in this thread Patch in this message | | | Date | Wed, 02 Nov 2011 15:15:09 -0700 | From | Greg KH <> | Subject | [103/107] vm: fix vm_pgoff wrap in stack expansion |
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2.6.32-longterm review patch. If anyone has any objections, please let us know.
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From: Linus Torvalds <torvalds@linux-foundation.org>
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 ÅwiÄcki, using his nasty system call fuzzer tool. Good job.
Reported-and-tested-by: Robert ÅwiÄcki <robert@swiecki.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- mm/mmap.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/mm/mmap.c +++ b/mm/mmap.c @@ -1680,10 +1680,13 @@ static int expand_downwards(struct vm_ar 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);
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