xfs: sb_spino_align is not verified

It's just read in from the superblock and used without doing any
validity checks at all on the value.

Fixes: fb4f2b4 ("xfs: add sparse inode chunk alignment superblock field")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: dgchinner

fs/xfs/libxfs/xfs_sb.c

@@ -398,6 +398,20 @@ xfs_validate_sb_common(
 					 sbp->sb_inoalignmt, align);
 				return -EINVAL;
 			}
+
+			if (!sbp->sb_spino_align ||
+			    sbp->sb_spino_align > sbp->sb_inoalignmt ||
+			    (sbp->sb_inoalignmt % sbp->sb_spino_align) != 0) {
+				xfs_warn(mp,
+				"Sparse inode alignment (%u) is invalid.",
+					sbp->sb_spino_align);
+				return -EINVAL;
+			}
+		} else if (sbp->sb_spino_align) {
+			xfs_warn(mp,
+				"Sparse inode alignment (%u) should be zero.",
+				sbp->sb_spino_align);
+			return -EINVAL;
 		}
 	} else if (sbp->sb_qflags & (XFS_PQUOTA_ENFD | XFS_GQUOTA_ENFD |
 				XFS_PQUOTA_CHKD | XFS_GQUOTA_CHKD)) {