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xfs: fix zero byte checking in the superblock scrubber

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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: 21fb4cb198 ("xfs: scrub the secondary superblocks")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong 2024-12-02 10:57:42 -08:00
parent 06b20ef09b
commit c004a793e0
1 changed files with 29 additions and 2 deletions
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31
fs/xfs/scrub/agheader.c
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@ -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);