xfs: sb verifier doesn't handle uncached sb buffer

The verifier checks explicitly for bp->b_bn == XFS_SB_DADDR to match the primary superblock buffer, but the primary superblock is an uncached buffer and so bp->b_bn is always -1ULL. Hence this never matches and the CRC error reporting is wholly dependent on the mount superblock already being populated so CRC feature checks pass and allow CRC errors to be reported. Fix this so that the primary superblock CRC error reporting is not dependent on already having read the superblock into memory. Signed-off-by: Dave Chinner <[email protected]> Reviewed-by: Darrick J. Wong <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Darrick J. Wong <[email protected]>
torvalds · Aug 19, 2021 · 8cf07f3 · 8cf07f3
1 parent e5f2e54
commit 8cf07f3
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diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
@@ -636,7 +636,7 @@ xfs_sb_read_verify(
 
  if (!xfs_buf_verify_cksum(bp, XFS_SB_CRC_OFF)) {
  /* Only fail bad secondaries on a known V5 filesystem */
- if (bp->b_bn == XFS_SB_DADDR ||
+ if (bp->b_maps[0].bm_bn == XFS_SB_DADDR ||
  xfs_sb_version_hascrc(&mp->m_sb)) {
  error = -EFSBADCRC;
  goto out_error;

diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
@@ -133,7 +133,12 @@ struct xfs_buf {
  * fast-path on locking.
  */
  struct rhash_head b_rhash_head; /* pag buffer hash node */
- xfs_daddr_t b_bn; /* block number of buffer */
+
+ /*
+ * b_bn is the cache index. Do not use directly, use b_maps[0].bm_bn
+ * for the buffer disk address instead.
+ */
+ xfs_daddr_t b_bn;
  int b_length; /* size of buffer in BBs */
  atomic_t b_hold; /* reference count */
  atomic_t b_lru_ref; /* lru reclaim ref count */