xfs: check leaf attribute block freemap in verifier

Check the leaf attribute freemap when we're verifying the block.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NCarlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_attr_leaf.c

@@ -244,6 +244,8 @@ xfs_attr3_leaf_verify(
 	struct xfs_attr_leafblock	*leaf = bp->b_addr;
 	struct xfs_perag		*pag = bp->b_pag;
 	struct xfs_attr_leaf_entry	*entries;
+	uint16_t			end;
+	int				i;
 
 	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr, leaf);
 
@@ -289,6 +291,26 @@ xfs_attr3_leaf_verify(
 	/* XXX: need to range check rest of attr header values */
 	/* XXX: hash order check? */
 
+	/*
+	 * Quickly check the freemap information.  Attribute data has to be
+	 * aligned to 4-byte boundaries, and likewise for the free space.
+	 */
+	for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
+		if (ichdr.freemap[i].base > mp->m_attr_geo->blksize)
+			return __this_address;
+		if (ichdr.freemap[i].base & 0x3)
+			return __this_address;
+		if (ichdr.freemap[i].size > mp->m_attr_geo->blksize)
+			return __this_address;
+		if (ichdr.freemap[i].size & 0x3)
+			return __this_address;
+		end = ichdr.freemap[i].base + ichdr.freemap[i].size;
+		if (end < ichdr.freemap[i].base)
+			return __this_address;
+		if (end > mp->m_attr_geo->blksize)
+			return __this_address;
+	}
+
 	return NULL;
 }