diff options
| author | Jerry Chu <hkchu@google.com> | 2012-10-22 11:26:36 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-10-23 02:42:56 -0400 |
| commit | 37561f68bd527ec39076e32effdc7b1dcdfb17ea (patch) | |
| tree | 3b15ff453617ee5ef52e5f7a9885770b4172bc0a /net/ipv4/tcp_timer.c | |
| parent | 0b63bf1fe6f9ed1ec4148e8896f4522e08476b80 (diff) | |
tcp: Reject invalid ack_seq to Fast Open sockets
A packet with an invalid ack_seq may cause a TCP Fast Open socket to switch
to the unexpected TCP_CLOSING state, triggering a BUG_ON kernel panic.
When a FIN packet with an invalid ack_seq# arrives at a socket in
the TCP_FIN_WAIT1 state, rather than discarding the packet, the current
code will accept the FIN, causing state transition to TCP_CLOSING.
This may be a small deviation from RFC793, which seems to say that the
packet should be dropped. Unfortunately I did not expect this case for
Fast Open hence it will trigger a BUG_ON panic.
It turns out there is really nothing bad about a TFO socket going into
TCP_CLOSING state so I could just remove the BUG_ON statements. But after
some thought I think it's better to treat this case like TCP_SYN_RECV
and return a RST to the confused peer who caused the unacceptable ack_seq
to be generated in the first place.
Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_timer.c')
| -rw-r--r-- | net/ipv4/tcp_timer.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index fc04711e80c8..d47c1b4421a3 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -347,8 +347,8 @@ void tcp_retransmit_timer(struct sock *sk) return; } if (tp->fastopen_rsk) { - BUG_ON(sk->sk_state != TCP_SYN_RECV && - sk->sk_state != TCP_FIN_WAIT1); + WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV && + sk->sk_state != TCP_FIN_WAIT1); tcp_fastopen_synack_timer(sk); /* Before we receive ACK to our SYN-ACK don't retransmit * anything else (e.g., data or FIN segments). |