| From | Jiri Slaby <> | Subject | [PATCH 3.12 056/111] mm: rmap: fix use-after-free in __put_anon_vma | Date | Mon, 23 Jun 2014 10:31:31 +0200 |
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From: Andrey Ryabinin <a.ryabinin@samsung.com>
3.12-stable review patch. If anyone has any objections, please let me know.
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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: Jiri Slaby <jslaby@suse.cz> --- mm/rmap.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/mm/rmap.c b/mm/rmap.c index 6e3139835e00..91ab22878103 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1681,10 +1681,9 @@ 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); } #ifdef CONFIG_MIGRATION -- 2.0.0
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