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authorDave Chinner <dchinner@redhat.com>2014-06-06 16:00:43 +1000
committerDave Chinner <david@fromorbit.com>2014-06-06 16:00:43 +1000
commit556b8883cfac3d3203557e161ea8005f8b5479b2 (patch)
treed928587238b976cd90ef90494769eab3af6f95c4 /fs/xfs
parent1f6d64829db78a7e1d63e15c9f48f0a5d2b5a679 (diff)
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xfs: xfs_readsb needs to check for magic numbers
Commit daba542 ("xfs: skip verification on initial "guess" superblock read") dropped the use of a verifier for the initial superblock read so we can probe the sector size of the filesystem stored in the superblock. It, however, now fails to validate that what was read initially is actually an XFS superblock and hence will fail the sector size check and return ENOSYS. This causes probe-based mounts to fail because it expects XFS to return EINVAL when it doesn't recognise the superblock format. cc: <stable@vger.kernel.org> Reported-by: Plamen Petrov <plamen.sisi@gmail.com> Tested-by: Plamen Petrov <plamen.sisi@gmail.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/xfs_mount.c23
1 files changed, 17 insertions, 6 deletions
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 944f3d9456a8..a9e29ea37620 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -323,8 +323,19 @@ reread:
/*
* Initialize the mount structure from the superblock.
*/
- xfs_sb_from_disk(&mp->m_sb, XFS_BUF_TO_SBP(bp));
- xfs_sb_quota_from_disk(&mp->m_sb);
+ xfs_sb_from_disk(sbp, XFS_BUF_TO_SBP(bp));
+ xfs_sb_quota_from_disk(sbp);
+
+ /*
+ * If we haven't validated the superblock, do so now before we try
+ * to check the sector size and reread the superblock appropriately.
+ */
+ if (sbp->sb_magicnum != XFS_SB_MAGIC) {
+ if (loud)
+ xfs_warn(mp, "Invalid superblock magic number");
+ error = EINVAL;
+ goto release_buf;
+ }
/*
* We must be able to do sector-sized and sector-aligned IO.
@@ -337,11 +348,11 @@ reread:
goto release_buf;
}
- /*
- * Re-read the superblock so the buffer is correctly sized,
- * and properly verified.
- */
if (buf_ops == NULL) {
+ /*
+ * Re-read the superblock so the buffer is correctly sized,
+ * and properly verified.
+ */
xfs_buf_relse(bp);
sector_size = sbp->sb_sectsize;
buf_ops = loud ? &xfs_sb_buf_ops : &xfs_sb_quiet_buf_ops;