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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-04-13 08:07:28 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-07 12:32:49 -0800 |
| commit | c1bf02fadd5bbd27c6ba3a8de4c8cdc0e36231e7 (patch) | |
| tree | 013db061a5610073660d8e78a2cbe3ba8e4315ab | |
| parent | d77e3459f7edf03567024ad9442dace4bcb81b9c (diff) | |
| download | lwn-c1bf02fadd5bbd27c6ba3a8de4c8cdc0e36231e7.tar.gz lwn-c1bf02fadd5bbd27c6ba3a8de4c8cdc0e36231e7.zip | |
vm: fix vm_pgoff wrap in stack expansion
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | mm/mmap.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 292afec03615..537b36584e9a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1680,10 +1680,13 @@ 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); |