From 196c55ab344602fa0768a6a50b86f63b5744d106 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Fri, 6 Jun 2014 16:00:43 +1000 Subject: xfs: xfs_readsb needs to check for magic numbers commit 556b8883cfac3d3203557e161ea8005f8b5479b2 upstream. 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. Reported-by: Plamen Petrov Tested-by: Plamen Petrov Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Dave Chinner Signed-off-by: Greg Kroah-Hartman --- fs/xfs/xfs_mount.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) (limited to 'fs/xfs') diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index f96c05669a9e..c6ff3cf5a5bb 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -320,8 +320,19 @@ 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. @@ -334,11 +345,11 @@ 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; -- cgit v1.2.3