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authorAndrey Ryabinin <a.ryabinin@samsung.com>2014-06-06 19:09:30 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-06 08:53:41 -0700
commit624483f3ea82598ab0f62f1bdb9177f531ab1892 (patch)
treedb14accead23e539ddbb9ff5eb9994179c69e6b8 /mm/rmap.c
parent951e273060d15b233a7f7ccaf76ba682b5b05a03 (diff)
downloadlinux-624483f3ea82598ab0f62f1bdb9177f531ab1892.tar.bz2
mm: rmap: fix use-after-free in __put_anon_vma
While working address sanitizer for kernel I've discovered use-after-free bug in __put_anon_vma. For the last anon_vma, anon_vma->root freed before child anon_vma. Later in anon_vma_free(anon_vma) we are referencing to already freed anon_vma->root to check rwsem. This fixes it by freeing the child anon_vma before freeing anon_vma->root. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: <stable@vger.kernel.org> # v3.0+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 9c3e77396d1a..83bfafabb47b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1564,10 +1564,9 @@ void __put_anon_vma(struct anon_vma *anon_vma)
{
struct anon_vma *root = anon_vma->root;
+ anon_vma_free(anon_vma);
if (root != anon_vma && atomic_dec_and_test(&root->refcount))
anon_vma_free(root);
-
- anon_vma_free(anon_vma);
}
static struct anon_vma *rmap_walk_anon_lock(struct page *page,