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authorJohannes Weiner <hannes@cmpxchg.org>2009-01-06 14:40:31 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 15:59:10 -0800
commitdcd4a049b9751828c516c59709f3fdf50436df85 (patch)
tree126fe11368da94f0c2e11ed586a870fa1b02f0a6
parent084f71ae5ceeb16734d8ac47559d3c718456a865 (diff)
downloadlinux-dcd4a049b9751828c516c59709f3fdf50436df85.tar.bz2
mm: check for no mmaps in exit_mmap()
When dup_mmap() ooms we can end up with mm->mmap == NULL. The error path does mmput() and unmap_vmas() gets a NULL vma which it dereferences. In exit_mmap() there is nothing to do at all for this case, we can cancel the callpath right there. [akpm@linux-foundation.org: add sorely-needed comment] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/mmap.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 1f97d8aa9b05..a910c045cfd4 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2090,6 +2090,9 @@ void exit_mmap(struct mm_struct *mm)
arch_exit_mmap(mm);
mmu_notifier_release(mm);
+ if (!mm->mmap) /* Can happen if dup_mmap() received an OOM */
+ return;
+
if (mm->locked_vm) {
vma = mm->mmap;
while (vma) {