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xfs: validate sb_logsunit is a multiple of the fs blocksize

PATCH In review Darrick J. Wong 2 participants 3 messages Oct 24, 2017 XFS filesystem

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#0 lore raw

PATCH 1/1 xfs: validate sb_logsunit is a multiple of the fs blocksize

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.

---
 fs/xfs/xfs_log.c |    6 ++++++
 1 file changed, 6 insertions(+)
fs/xfs/xfs_log.c +6 -0
index d729e00..da4dcab 100644
@@ -659,6 +659,12 @@ 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;
 	}
 	if (error) {
 		if (xfs_sb_version_hascrc(&mp->m_sb)) {
#1 lore raw
Quoted 15 lines · Darrick J. Wong

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.

---
 fs/xfs/xfs_log.c |    6 ++++++
 1 file changed, 6 insertions(+)
fs/xfs/xfs_log.c +0 -0
index d729e00..da4dcab 100644

fs/xfs/xfs_log.c xfs_log_mount( · line 667

Quoted 9 lines
fs/xfs/xfs_log.c +6 -0
@@ -659,6 +659,12 @@ 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;

Looks fine, but I notice that the error handling just below only fails the mount on v5 filesystems. Otherwise we warn and carry on. I'm not sure why that is.. but is this a crash vector on v4 filesystems as well?

Brian

Quoted 7 lines
fs/xfs/xfs_log.c +0 -1
 	}
 	if (error) {
 		if (xfs_sb_version_hascrc(&mp->m_sb)) {
--

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#2 lore raw
Quoted 21 lines · Brian Foster
Quoted 20 lines · Darrick J. Wong

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.

---
 fs/xfs/xfs_log.c |    6 ++++++
 1 file changed, 6 insertions(+)
fs/xfs/xfs_log.c +2 -0
index d729e00..da4dcab 100644
@@ -659,6 +659,12 @@ 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) {
Quoted 8 lines

fs/xfs/xfs_log.c xfs_log_mount( · line 667

Quoted 4 lines
fs/xfs/xfs_log.c +4 -0
+		xfs_warn(mp,
+		"log stripe unit %u bytes must be a multiple of block size",
+			 mp->m_sb.sb_logsunit);
+		error = -EINVAL;

Looks fine, but I notice that the error handling just below only fails the mount on v5 filesystems. Otherwise we warn and carry on. I'm not sure why that is.. but is this a crash vector on v4 filesystems as well?

It is a crash vector on v4 as well, so I'll be stricter about failing the mount. I was trying to be cautious about this since there haven't
been general complaints about v4 filesystems, but ... eh. A crash is a
crash. :)

--D

Quoted 14 lines

Brian

Quoted 7 lines
fs/xfs/xfs_log.c +0 -1
 	}
 	if (error) {
 		if (xfs_sb_version_hascrc(&mp->m_sb)) {
--

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