From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936503AbdCJMK7 (ORCPT ); Fri, 10 Mar 2017 07:10:59 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45051 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936493AbdCJMK4 (ORCPT ); Fri, 10 Mar 2017 07:10:56 -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, "Theodore Ts'o" Date: Fri, 10 Mar 2017 11:46:10 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 023/199] ext4: add sanity checking to count_overhead() In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 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 3.2.87-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit c48ae41bafe31e9a66d8be2ced4e42a6b57fa814 upstream. The commit "ext4: sanity check the block and cluster size at mount time" should prevent any problems, but in case the superblock is modified while the file system is mounted, add an extra safety check to make sure we won't overrun the allocated buffer. Signed-off-by: Theodore Ts'o Signed-off-by: Ben Hutchings --- fs/ext4/super.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3180,10 +3180,15 @@ static int count_overhead(struct super_b ext4_set_bit(s++, buf); count++; } - for (j = ext4_bg_num_gdb(sb, grp); j > 0; j--) { - ext4_set_bit(EXT4_B2C(sbi, s++), buf); - count++; + j = ext4_bg_num_gdb(sb, grp); + if (s + j > EXT4_BLOCKS_PER_GROUP(sb)) { + ext4_error(sb, "Invalid number of block group " + "descriptor blocks: %d", j); + j = EXT4_BLOCKS_PER_GROUP(sb) - s; } + count += j; + for (; j > 0; j--) + ext4_set_bit(EXT4_B2C(sbi, s++), buf); } if (!count) return 0;