From: Andrey Ryabinin <a.ryabinin@samsung.com>
Date: Fri, 6 Jun 2014 15:09:30 +0000 (+0400)
Subject: mm: rmap: fix use-after-free in __put_anon_vma
X-Git-Tag: omap-for-v3.16/fixes-against-rc1~99
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=624483f3ea82598ab0f62f1bdb9177f531ab1892;p=pandora-kernel.git

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>
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