tree db14accead23e539ddbb9ff5eb9994179c69e6b8
parent 951e273060d15b233a7f7ccaf76ba682b5b05a03
author Andrey Ryabinin <a.ryabinin@samsung.com> 1402067370 +0400
committer Linus Torvalds <torvalds@linux-foundation.org> 1402070021 -0700

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>