Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756426AbaGHT1o (ORCPT ); Tue, 8 Jul 2014 15:27:44 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54202 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755711AbaGHTIl (ORCPT ); Tue, 8 Jul 2014 15:08:41 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Peter Zijlstra" , "Andrey Ryabinin" , "Linus Torvalds" Date: Tue, 08 Jul 2014 20:01:50 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 078/125] mm: rmap: fix use-after-free in __put_anon_vma In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Andrey Ryabinin 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: Ben Hutchings --- mm/rmap.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1671,10 +1671,9 @@ void __put_anon_vma(struct anon_vma *ano { 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/