From 655c2dadb43db14175b4e4447dbeca7c1d4f6522 Mon Sep 17 00:00:00 2001 From: Wei Wang Date: Mon, 11 Sep 2017 08:23:00 +0200 Subject: [PATCH] tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0 CVE-2017-14106 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 Signed-off-by: Wei Wang Signed-off-by: Eric Dumazet Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Signed-off-by: David S. Miller (cherry picked from commit 499350a5a6e7512d9ed369ed63a4244b6536f4f8) Signed-off-by: Po-Hsu Lin Acked-by: Stefan Bader Acked-by: Colin King Signed-off-by: Stefan Bader --- net/ipv4/tcp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 53fa3a4275de..cae2a73cd970 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2298,6 +2298,10 @@ 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); -- 2.39.5