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authorAndrey Ryabinin <a.ryabinin@samsung.com>2014-06-06 19:09:30 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-11 11:54:13 -0700
commit3ed6413483c7a43b9d38111357ce99afab441717 (patch)
treefcd304564241cac87693e76f0d2ae170f588d8db
parent395982ce12b3aba14a197ead3e5828e77e11aec1 (diff)
mm: rmap: fix use-after-free in __put_anon_vma
commit 624483f3ea82598ab0f62f1bdb9177f531ab1892 upstream. 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> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--mm/rmap.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index d3cbac508c2f..5d91bb71e751 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1554,10 +1554,9 @@ 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,