From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933525Ab3GCSzW (ORCPT ); Wed, 3 Jul 2013 14:55:22 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:20124 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933204Ab3GCSkz (ORCPT ); Wed, 3 Jul 2013 14:40:55 -0400 X-Authority-Analysis: v=2.0 cv=KtrPKBqN c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=Ciwy3NGCPMMA:10 a=ShVjDrTO4gIA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=b5akoMxLmsgA:10 a=VwQbUJbxAAAA:8 a=Z4Rwk6OoAAAA:8 a=ddWQQ7q1T1FyLl4_7q4A:9 a=jbrJJM5MRmoA:10 a=jeBq3FmKZ4MA:10 a=8uvNL9BktnWztIA3:21 a=4fYOt1fVFRDT508G:21 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Message-Id: <20130703184047.462216856@goodmis.org> User-Agent: quilt/0.60-1 Date: Wed, 03 Jul 2013 14:39:14 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Krzysztof Strasburger , OGAWA Hirofumi , Andrew Morton Subject: [017/141] fat: fix possible overflow for fat_clusters References: <20130703183857.307196999@goodmis.org> Content-Disposition: inline; filename=0017-fat-fix-possible-overflow-for-fat_clusters.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.6.11.6 stable review patch. If anyone has any objections, please let me know. ------------------ From: OGAWA Hirofumi [ Upstream commit 7b92d03c3239f43e5b86c9cc9630f026d36ee995 ] Intermediate value of fat_clusters can be overflowed on 32bits arch. Reported-by: Krzysztof Strasburger Signed-off-by: OGAWA Hirofumi Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Steven Rostedt --- fs/fat/inode.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 05e897f..ca5241f 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -1212,6 +1212,19 @@ static int fat_read_root(struct inode *inode) return 0; } +static unsigned long calc_fat_clusters(struct super_block *sb) +{ + struct msdos_sb_info *sbi = MSDOS_SB(sb); + + /* Divide first to avoid overflow */ + if (sbi->fat_bits != 12) { + unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits; + return ent_per_sec * sbi->fat_length; + } + + return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits; +} + /* * Read the super block of an MS-DOS FS. */ @@ -1409,7 +1422,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat, sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12; /* check that FAT table does not overflow */ - fat_clusters = sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits; + fat_clusters = calc_fat_clusters(sb); total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT); if (total_clusters > MAX_FAT(sb)) { if (!silent) -- 1.7.10.4