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authorWei Wang <weiwan@google.com>2017-05-18 11:22:33 -0700
committerDavid S. Miller <davem@davemloft.net>2017-05-21 13:24:47 -0400
commit499350a5a6e7512d9ed369ed63a4244b6536f4f8 (patch)
tree4b81c6f4df9119704c570e73a6cdde12094e1c89 /net/ipv4
parent23416e230416a9201561f1db553b1515e9959f6a (diff)
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 <andreyknvl@google.com> Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1e4c76d2b827..842b575f8fdd 100644
--- 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);