7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Aldo Ariel Panzardo commit 3df5e5aaa3bc0913236c48ab29b7df3a785aa29f upstream. xfs_da3_node_verify() bounds the node entry count against the larger of the directory and attribute geometries because, as a buffer verifier, it cannot tell whether the block belongs to the directory or the attribute tree. When the directory block size exceeds the fs block size (e.g. mkfs.xfs -n size=64k -b size=4k), an attribute node buffer is a single fs block that holds only m_attr_geo->node_ents entries, yet a crafted attr node may claim a count up to m_dir_geo->node_ents and still pass the verifier. xfs_da3_node_lookup_int() then indexes btree[] up to that count during its binary search -- an out-of-bounds read via getxattr/listxattr on a mounted crafted image. The buffer verifier is the wrong place to tighten this: it has no fork context, and the transaction-less read path used by getxattr does not run xfs_da3_node_set_type() either. xfs_da3_node_lookup_int(), on the other hand, always runs on that path and holds args->geo, the geometry of the fork actually being searched. Bound the entry count against args->geo->node_ents there, before walking the entries. Fixes: 7ab610f9e0f1 ("xfs: move node entry counts to xfs_da_geometry") Cc: stable@vger.kernel.org Signed-off-by: Aldo Ariel Panzardo Reviewed-by: Darrick J. Wong Signed-off-by: Carlos Maiolino Signed-off-by: Greg Kroah-Hartman --- fs/xfs/libxfs/xfs_da_btree.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) --- a/fs/xfs/libxfs/xfs_da_btree.c +++ b/fs/xfs/libxfs/xfs_da_btree.c @@ -1787,6 +1787,20 @@ xfs_da3_node_lookup_int( } else expected_level--; + /* + * The node verifier cannot tell whether this block belongs to + * the directory or the attribute tree, so it only bounds the + * entry count against the larger of the two geometries. Here + * args->geo is the geometry of the fork we are actually + * searching, so reject a count that would walk btree[] off the + * end of this node buffer. + */ + if (nodehdr.count > args->geo->node_ents) { + xfs_buf_mark_corrupt(blk->bp); + xfs_da_mark_sick(args); + return -EFSCORRUPTED; + } + max = nodehdr.count; blk->hashval = be32_to_cpu(btree[max - 1].hashval);