From b40b4f79ce789e9e28d382c85006f62be2725282 Mon Sep 17 00:00:00 2001 From: Srinivas Aji Date: Thu, 3 May 2007 17:32:28 -0700 Subject: [PATCH] [TCP]: zero out rx_opt in tcp_disconnect() When the server drops its connection, NFS client reconnects using the same socket after disconnecting. If the new connection's SYN,ACK doesn't contain the TCP timestamp option and the old connection's did, tp->tcp_header_len is recomputed assuming no timestamp header but tp->rx_opt.tstamp_ok remains set. Then tcp_build_and_update_options() adds in a timestamp option past the end of the allocated TCP header, overwriting TCP data, or when the data is in skb_shinfo(skb)->frags[], overwriting skb_shinfo(skb) causing a crash soon after. (The issue was debugged from such a crash.) Similarly, wscale_ok and sack_ok also get set based on the SYN,ACK packet but not reset on disconnect, since they are zeroed out at initialization. The patch zeroes out the entire tp->rx_opt struct in tcp_disconnect() to avoid this sort of problem. Signed-off-by: Srinivas Aji Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index d6e488668171..8b124eafbb90 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1760,8 +1760,7 @@ int tcp_disconnect(struct sock *sk, int flags) tcp_clear_retrans(tp); inet_csk_delack_init(sk); tcp_init_send_head(sk); - tp->rx_opt.saw_tstamp = 0; - tcp_sack_reset(&tp->rx_opt); + memset(&tp->rx_opt, 0, sizeof(tp->rx_opt)); __sk_dst_reset(sk); BUG_TRAP(!inet->num || icsk->icsk_bind_hash); -- 2.20.1