tipc: improve size validations for received domain records

commit 9aa422a upstream.

The function tipc_mon_rcv() allows a node to receive and process
domain_record structs from peer nodes to track their views of the
network topology.

This patch verifies that the number of members in a received domain
record does not exceed the limit defined by MAX_MON_DOMAIN, something
that may otherwise lead to a stack overflow.

tipc_mon_rcv() is called from the function tipc_link_proto_rcv(), where
we are reading a 32 bit message data length field into a uint16.  To
avert any risk of bit overflow, we add an extra sanity check for this in
that function.  We cannot see that happen with the current code, but
future designers being unaware of this risk, may introduce it by
allowing delivery of very large (> 64k) sk buffers from the bearer
layer.  This potential problem was identified by Eric Dumazet.

This fixes CVE-2022-0435

Reported-by: Samuel Page <[email protected]>
Reported-by: Eric Dumazet <[email protected]>
Fixes: 35c55c9 ("tipc: add neighbor monitoring framework")
Signed-off-by: Jon Maloy <[email protected]>
Reviewed-by: Xin Long <[email protected]>
Reviewed-by: Samuel Page <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

net/tipc/link.c

@@ -1579,13 +1579,16 @@ static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
 	u16 peers_tol = msg_link_tolerance(hdr);
 	u16 peers_prio = msg_linkprio(hdr);
 	u16 rcv_nxt = l->rcv_nxt;
-	u16 dlen = msg_data_sz(hdr);
+	u32 dlen = msg_data_sz(hdr);
 	int mtyp = msg_type(hdr);
 	bool reply = msg_probe(hdr);
 	void *data;
 	char *if_name;
 	int rc = 0;
 
+	if (dlen > U16_MAX)
+		goto exit;
+
 	if (tipc_link_is_blocked(l) || !xmitq)
 		goto exit;
 

net/tipc/monitor.c

@@ -457,6 +457,8 @@ void tipc_mon_rcv(struct net *net, void *data, u16 dlen, u32 addr,
 	state->probing = false;
 
 	/* Sanity check received domain record */
+	if (new_member_cnt > MAX_MON_DOMAIN)
+		return;
 	if (dlen < dom_rec_len(arrv_dom, 0))
 		return;
 	if (dlen != dom_rec_len(arrv_dom, new_member_cnt))