tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0

When tcp_disconnect() is called, inet_csk_delack_init() sets icsk->icsk_ack.rcv_mss to 0. This could potentially cause tcp_recvmsg() => tcp_cleanup_rbuf() => __tcp_select_window() call path to have division by 0 issue. So this patch initializes rcv_mss to TCP_MIN_MSS instead of 0. Reported-by: Andrey Konovalov <[email protected]> Signed-off-by: Wei Wang <[email protected]> Signed-off-by: Eric Dumazet <[email protected]> Signed-off-by: Neal Cardwell <[email protected]> Signed-off-by: Yuchung Cheng <[email protected]> Signed-off-by: David S. Miller <[email protected]>
linux-surface · May 21, 2017 · 499350a · 499350a
1 parent 23416e2
commit 499350a
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
@@ -2320,6 +2320,10 @@ int tcp_disconnect(struct sock *sk, int flags)
 	tcp_set_ca_state(sk, TCP_CA_Open);
 	tcp_clear_retrans(tp);
 	inet_csk_delack_init(sk);
+	/* Initialize rcv_mss to TCP_MIN_MSS to avoid division by 0
+	 * issue in __tcp_select_window()
+	 */
+	icsk->icsk_ack.rcv_mss = TCP_MIN_MSS;
 	tcp_init_send_head(sk);
 	memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
 	__sk_dst_reset(sk);