From: Darrick J. Wong djwong@kernel.org
commit c004a793e0ec34047c3bd423bcd8966f5fac88dc upstream.
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 | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-)
diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c index da30f926cbe66d..0f2f1852d58fe7 100644 --- a/fs/xfs/scrub/agheader.c +++ b/fs/xfs/scrub/agheader.c @@ -59,6 +59,30 @@ 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_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 +99,7 @@ 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; @@ -350,8 +375,8 @@ 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);