From: "Darrick J. Wong" Subject: [PATCH 2/4] ext4: validate external journal superblock checksum Date: Wed, 10 Sep 2014 17:28:32 -0700 Message-ID: <20140911002831.10109.84707.stgit@birch.djwong.org> References: <20140911002818.10109.51772.stgit@birch.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: tytso@mit.edu, darrick.wong@oracle.com Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:42267 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753328AbaIKA2h (ORCPT ); Wed, 10 Sep 2014 20:28:37 -0400 In-Reply-To: <20140911002818.10109.51772.stgit@birch.djwong.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: If the external journal device has metadata_csum enabled, verify that the superblock checksum matches the block before we try to mount. Signed-off-by: Darrick J. Wong --- fs/ext4/super.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 7045f1d..222ed5d 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4372,6 +4372,15 @@ static journal_t *ext4_get_dev_journal(struct super_block *sb, goto out_bdev; } + if ((le32_to_cpu(es->s_feature_ro_compat) & + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) && + es->s_checksum != ext4_superblock_csum(sb, es)) { + ext4_msg(sb, KERN_ERR, "external journal has " + "corrupt superblock"); + brelse(bh); + goto out_bdev; + } + if (memcmp(EXT4_SB(sb)->s_es->s_journal_uuid, es->s_uuid, 16)) { ext4_msg(sb, KERN_ERR, "journal UUID does not match"); brelse(bh);