Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933518AbcKILfg (ORCPT ); Wed, 9 Nov 2016 06:35:36 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:53930 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753485AbcKILFY (ORCPT ); Wed, 9 Nov 2016 06:05:24 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Polakov , Vladimir Davydov , Al Viro , Andrew Morton , Linus Torvalds Subject: [PATCH 4.8 019/138] mm/list_lru.c: avoid error-path NULL pointer deref Date: Wed, 9 Nov 2016 11:45:02 +0100 Message-Id: <20161109102845.638995270@linuxfoundation.org> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161109102844.808685475@linuxfoundation.org> References: <20161109102844.808685475@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1448 Lines: 44 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexander Polakov commit 1bc11d70b5db7c6bb1414b283d7f09b1fe1ac0d0 upstream. As described in https://bugzilla.kernel.org/show_bug.cgi?id=177821: After some analysis it seems to be that the problem is in alloc_super(). In case list_lru_init_memcg() fails it goes into destroy_super(), which calls list_lru_destroy(). And in list_lru_init() we see that in case memcg_init_list_lru() fails, lru->node is freed, but not set NULL, which then leads list_lru_destroy() to believe it is initialized and call memcg_destroy_list_lru(). memcg_destroy_list_lru() in turn can access lru->node[i].memcg_lrus, which is NULL. [akpm@linux-foundation.org: add comment] Signed-off-by: Alexander Polakov Acked-by: Vladimir Davydov Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/list_lru.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -554,6 +554,8 @@ int __list_lru_init(struct list_lru *lru err = memcg_init_list_lru(lru, memcg_aware); if (err) { kfree(lru->node); + /* Do this so a list_lru_destroy() doesn't crash: */ + lru->node = NULL; goto out; }