Merge pull request #16521 from opensourcerouting/fix/capability_toggles

bgpd: Clear previously allocated capabilities values before parsing a new OPEN

bgpd/bgp_packet.c

@@ -1804,6 +1804,23 @@ static int bgp_open_receive(struct peer_connection *connection,
 	mp_capability = 0;
 	optlen = stream_getc(peer->curr);
 
+	/* If we previously had some more capabilities e.g.:
+	 *   FQDN, SOFT_VERSION, we MUST clear the values we used
+	 *   before, to avoid using stale data.
+	 * Checking peer->cap is enough before checking for the real
+	 * data, but we don't have this check everywhere in the code,
+	 * thus let's clear the data here too before parsing the
+	 * capabilities.
+	 */
+	if (peer->hostname)
+		XFREE(MTYPE_BGP_PEER_HOST, peer->hostname);
+
+	if (peer->domainname)
+		XFREE(MTYPE_BGP_PEER_HOST, peer->domainname);
+
+	if (peer->soft_version)
+		XFREE(MTYPE_BGP_SOFT_VERSION, peer->soft_version);
+
 	/* Extended Optional Parameters Length for BGP OPEN Message */
 	if (optlen == BGP_OPEN_NON_EXT_OPT_LEN
 	    || CHECK_FLAG(peer->flags, PEER_FLAG_EXTENDED_OPT_PARAMS)) {