diff mbox series

[4/6] xfs: fix zero byte checking in the superblock scrubber

Message ID 173353139368.192136.9553326949796475388.stgit@frogsfrogsfrogs (mailing list archive)
State Not Applicable, archived
Headers show
Series [1/6] xfs: don't move nondir/nonreg temporary repair files to the metadir namespace | expand

Commit Message

Darrick J. Wong Dec. 7, 2024, 12:31 a.m. UTC 
From: Darrick J. Wong <djwong@kernel.org>

The logic to check that the region past the end of the superblock is all
zeroes is wrong -- we don't want to check only the bytes past the end of
the maximally sized ondisk superblock structure as currently defined in
xfs_format.h; we want to check the bytes beyond the end of the ondisk as
defined by the feature bits.

Port the superblock size logic from xfs_repair and then put it to use in
xfs_scrub.

Cc: <stable@vger.kernel.org> # v4.15
Fixes: 21fb4cb1981ef7 ("xfs: scrub the secondary superblocks")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/scrub/agheader.c |   31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c
index 88063d67cb5fd4..9f8c312dfd3c82 100644
--- a/fs/xfs/scrub/agheader.c
+++ b/fs/xfs/scrub/agheader.c
@@ -59,6 +59,32 @@  xchk_superblock_xref(
 	/* scrub teardown will take care of sc->sa for us */
 }
 
+/*
+ * Calculate the ondisk superblock size in bytes given the feature set of the
+ * mounted filesystem (aka the primary sb).  This is subtlely different from
+ * the logic in xfs_repair, which computes the size of a secondary sb given the
+ * featureset listed in the secondary sb.
+ */
+STATIC size_t
+xchk_superblock_ondisk_size(
+	struct xfs_mount	*mp)
+{
+	if (xfs_has_metadir(mp))
+		return offsetofend(struct xfs_dsb, sb_pad);
+	if (xfs_has_metauuid(mp))
+		return offsetofend(struct xfs_dsb, sb_meta_uuid);
+	if (xfs_has_crc(mp))
+		return offsetofend(struct xfs_dsb, sb_lsn);
+	if (xfs_sb_version_hasmorebits(&mp->m_sb))
+		return offsetofend(struct xfs_dsb, sb_bad_features2);
+	if (xfs_has_logv2(mp))
+		return offsetofend(struct xfs_dsb, sb_logsunit);
+	if (xfs_has_sector(mp))
+		return offsetofend(struct xfs_dsb, sb_logsectsize);
+	/* only support dirv2 or more recent */
+	return offsetofend(struct xfs_dsb, sb_dirblklog);
+}
+
 /*
  * Scrub the filesystem superblock.
  *
@@ -75,6 +101,7 @@  xchk_superblock(
 	struct xfs_buf		*bp;
 	struct xfs_dsb		*sb;
 	struct xfs_perag	*pag;
+	size_t			sblen;
 	xfs_agnumber_t		agno;
 	uint32_t		v2_ok;
 	__be32			features_mask;
@@ -388,8 +415,8 @@  xchk_superblock(
 	}
 
 	/* Everything else must be zero. */
-	if (memchr_inv(sb + 1, 0,
-			BBTOB(bp->b_length) - sizeof(struct xfs_dsb)))
+	sblen = xchk_superblock_ondisk_size(mp);
+	if (memchr_inv((char *)sb + sblen, 0, BBTOB(bp->b_length) - sblen))
 		xchk_block_set_corrupt(sc, bp);
 
 	xchk_superblock_xref(sc, bp);