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authorJohannes Weiner <hannes@cmpxchg.org>2009-01-06 14:40:31 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2009-05-02 10:24:45 -0700
commit664b8ee764c295ff3bfd9736094a036dcc0ebda2 (patch)
tree1ad84571f84138aa3f8c9c90d7cc62d00b2d041c /mm
parent5e7675e9c311b657bd75bcf7038d3d73e9b8e9e8 (diff)
mm: check for no mmaps in exit_mmap()
commit dcd4a049b9751828c516c59709f3fdf50436df85 upstream. 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> Reported-by: Kir Kolyshkin <kir@openvz.org> Tested-by: Kir Kolyshkin <kir@openvz.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'mm')
-rw-r--r--mm/mmap.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index ca12a9308436..2ae093ed2cac 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2068,6 +2068,9 @@ 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;
+
lru_add_drain();
flush_cache_mm(mm);
tlb = tlb_gather_mmu(mm, 1);