From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753260AbaKLBVi (ORCPT ); Tue, 11 Nov 2014 20:21:38 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:58503 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753205AbaKLBVf (ORCPT ); Tue, 11 Nov 2014 20:21:35 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tetsuo Handa , Christoph Hellwig , Al Viro Subject: [PATCH 3.17 046/319] fs: Fix theoretical division by 0 in super_cache_scan(). Date: Wed, 12 Nov 2014 10:13:04 +0900 Message-Id: <20141112011000.247882214@linuxfoundation.org> X-Mailer: git-send-email 2.1.3 In-Reply-To: <20141112010952.553519040@linuxfoundation.org> References: <20141112010952.553519040@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.17-stable 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 Signed-off-by: Greg Kroah-Hartman --- fs/super.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/super.c +++ b/fs/super.c @@ -80,6 +80,8 @@ static unsigned long super_cache_scan(st inodes = list_lru_count_node(&sb->s_inode_lru, sc->nid); dentries = list_lru_count_node(&sb->s_dentry_lru, sc->nid); total_objects = dentries + inodes + fs_objects + 1; + if (!total_objects) + total_objects = 1; /* proportion the scan between the caches */ dentries = mult_frac(sc->nr_to_scan, dentries, total_objects);