linux-kernel - [PATCH 4.14 083/117] xfs: validate sb_logsunit is a multiple of the fs blocksize

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Message-Id: <20200501131554.637574672@linuxfoundation.org>
Date:   Fri,  1 May 2020 15:21:59 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Brian Foster <bfoster@...hat.com>,
        Suraj Jitindar Singh <surajjs@...zon.com>
Subject: [PATCH 4.14 083/117] xfs: validate sb_logsunit is a multiple of the fs blocksize

From: Darrick J. Wong <darrick.wong@...cle.com>

commit 9c92ee208b1faa0ef2cc899b85fd0607b6fac7fe upstream.

Make sure the log stripe unit is sane before proceeding with mounting.
AFAICT this means that logsunit has to be 0, 1, or a multiple of the fs
block size.  Found this by setting the LSB of logsunit in xfs/350 and
watching the system crash as soon as we try to write to the log.

Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
Reviewed-by: Brian Foster <bfoster@...hat.com>
Signed-off-by: Suraj Jitindar Singh <surajjs@...zon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/xfs/xfs_log.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -608,6 +608,7 @@ xfs_log_mount(
 	xfs_daddr_t	blk_offset,
 	int		num_bblks)
 {
+	bool		fatal = xfs_sb_version_hascrc(&mp->m_sb);
 	int		error = 0;
 	int		min_logfsbs;
 
@@ -659,9 +660,20 @@ xfs_log_mount(
 			 XFS_FSB_TO_B(mp, mp->m_sb.sb_logblocks),
 			 XFS_MAX_LOG_BYTES);
 		error = -EINVAL;
+	} else if (mp->m_sb.sb_logsunit > 1 &&
+		   mp->m_sb.sb_logsunit % mp->m_sb.sb_blocksize) {
+		xfs_warn(mp,
+		"log stripe unit %u bytes must be a multiple of block size",
+			 mp->m_sb.sb_logsunit);
+		error = -EINVAL;
+		fatal = true;
 	}
 	if (error) {
-		if (xfs_sb_version_hascrc(&mp->m_sb)) {
+		/*
+		 * Log check errors are always fatal on v5; or whenever bad
+		 * metadata leads to a crash.
+		 */
+		if (fatal) {
 			xfs_crit(mp, "AAIEEE! Log failed size checks. Abort!");
 			ASSERT(0);
 			goto out_free_log;