Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760191AbaLLGyy (ORCPT ); Fri, 12 Dec 2014 01:54:54 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52598 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750868AbaLLGsJ (ORCPT ); Fri, 12 Dec 2014 01:48:09 -0500 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, "Christoph Hellwig" , "Al Viro" , "Tetsuo Handa" Date: Fri, 12 Dec 2014 06:14:25 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 050/164] fs: Fix theoretical division by 0 in super_cache_scan(). In-Reply-To: X-SA-Exim-Connect-IP: 2001:470:1f08:1539:c97:8151:cc89:c28d 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 3.2.65-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa commit 475d0db742e3755c6b267f48577ff7cbb7dfda0d upstream. total_objects could be 0 and is used as a denom. While total_objects is a "long", total_objects == 0 unlikely happens for 3.12 and later kernels because 32-bit architectures would not be able to hold (1 << 32) objects. However, total_objects == 0 may happen for kernels between 3.1 and 3.11 because total_objects in prune_super() was an "int" and (e.g.) x86_64 architecture might be able to hold (1 << 32) objects. Signed-off-by: Tetsuo Handa Reviewed-by: Christoph Hellwig Signed-off-by: Al Viro [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- fs/super.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/super.c +++ b/fs/super.c @@ -68,6 +68,8 @@ static int prune_super(struct shrinker * total_objects = sb->s_nr_dentry_unused + sb->s_nr_inodes_unused + fs_objects + 1; + if (!total_objects) + total_objects = 1; if (sc->nr_to_scan) { int dentries; -- 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/