[XFS] Check for invalid flags in xfs_attrlist_by_handle.

xfs_attrlist_by_handle should only take the ATTR_ flags for the root
namespaces. The ATTR_KERN* flags may change at anytime and expect special
preconditions that can't be guaranteed for userspace-originating requests.
For example passing down ATTR_KERNNOVAL through xfs_attrlist_by_handle
will hit an assert in debug builds currently.

SGI-PV: 983677

SGI-Modid: xfs-linux-melb:xfs-kern:31351a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

fs/xfs/linux-2.6/xfs_ioctl.c

@@ -468,6 +468,12 @@ xfs_attrlist_by_handle(
 	if (al_hreq.buflen > XATTR_LIST_MAX)
 		return -XFS_ERROR(EINVAL);
 
+	/*
+	 * Reject flags, only allow namespaces.
+	 */
+	if (al_hreq.flags & ~(ATTR_ROOT | ATTR_SECURE))
+		return -XFS_ERROR(EINVAL);
+
 	error = xfs_vget_fsop_handlereq(mp, parinode, &al_hreq.hreq, &inode);
 	if (error)
 		goto out;