xfrm_user: validate XFRM_MSG_NEWAE incoming ESN size harder

Kees Cook has pointed out that xfrm_replay_state_esn_len() is subject to wrapping issues. To ensure we are correctly ensuring that the two ESN structures are the same size compare both the overall size as reported by xfrm_replay_state_esn_len() and the internal length are the same. CVE-2017-7184 Signed-off-by: Andy Whitcroft <[email protected]> Acked-by: Steffen Klassert <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
ambv · Mar 29, 2017 · f843ee6 · f843ee6
1 parent 677e806
commit f843ee6
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
@@ -412,7 +412,11 @@ static inline int xfrm_replay_verify_len(struct xfrm_replay_state_esn *replay_es
 	up = nla_data(rp);
 	ulen = xfrm_replay_state_esn_len(up);
 
-	if (nla_len(rp) < ulen || xfrm_replay_state_esn_len(replay_esn) != ulen)
+	/* Check the overall length and the internal bitmap length to avoid
+	 * potential overflow. */
+	if (nla_len(rp) < ulen ||
+	    xfrm_replay_state_esn_len(replay_esn) != ulen ||
+	    replay_esn->bmp_len != up->bmp_len)
 		return -EINVAL;
 
 	if (up->replay_window > up->bmp_len * sizeof(__u32) * 8)