From 37b4a2965399a7f397ac080453fe6e031cfdb48e Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Fri, 6 Jun 2014 19:09:30 +0400 Subject: 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 Acked-by: Peter Zijlstra Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/rmap.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index d3cbac508c2..5d91bb71e75 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, -- cgit v1.2.3