From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761204AbbA1ERq (ORCPT ); Tue, 27 Jan 2015 23:17:46 -0500 Received: from mail.kernel.org ([198.145.29.136]:38204 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761174AbbA1ERn (ORCPT ); Tue, 27 Jan 2015 23:17:43 -0500 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Tetsuo Handa , Al Viro , Zefan Li Subject: [PATCH 3.4 045/177] fs: Fix theoretical division by 0 in super_cache_scan(). Date: Wed, 28 Jan 2015 12:07:37 +0800 Message-Id: <1422418236-12852-90-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1422418050-12581-1-git-send-email-lizf@kernel.org> References: <1422418050-12581-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tetsuo Handa 3.4.106-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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 [lizf: Backported to 3.4: adjust context] Signed-off-by: Zefan Li --- fs/super.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/super.c b/fs/super.c index 3c520a5..d0154e5 100644 --- a/fs/super.c +++ b/fs/super.c @@ -69,6 +69,8 @@ static int prune_super(struct shrinker *shrink, struct shrink_control *sc) 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; -- 1.9.1