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authorLinus Torvalds <torvalds@linux-foundation.org>2011-04-13 08:07:28 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2011-04-21 14:32:18 -0700
commit833923adc70f9493f0860ffff7e326612c1ff513 (patch)
treec3211304afdbedba0b0cfe3f4981a3c6419d701d /mm
parent1be99f6c95e6c887756f789a60d15771235acd0c (diff)
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/mmap.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 2ec8eb5a9cd..8c05e5b43b6 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1814,11 +1814,14 @@ 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;
- perf_event_mmap(vma);
+ error = -ENOMEM;
+ if (grow <= vma->vm_pgoff) {
+ error = acct_stack_growth(vma, size, grow);
+ if (!error) {
+ vma->vm_start = address;
+ vma->vm_pgoff -= grow;
+ perf_event_mmap(vma);
+ }
}
}
vma_unlock_anon_vma(vma);