Commit 7b514a88 authored Jan 10, 2013 by Eric Dumazet Committed by David S. Miller Jan 10, 2013

tcp: accept RST without ACK flag



commit c3ae62af (tcp: should drop incoming frames without ACK flag
set) added a regression on the handling of RST messages.

RST should be allowed to come even without ACK bit set. We validate
the RST by checking the exact sequence, as requested by RFC 793 and
5961 3.2, in tcp_validate_incoming()

Reported-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Tested-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent cb59c87d

net/ipv4/tcp_input.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -5543,7 +5543,7 @@ slow_path:
		if (len < (th->doff << 2) \|\| tcp_checksum_complete_user(sk, skb))
		goto csum_error;

		if (!th->ack)
		if (!th->ack && !th->rst)
		goto discard;

		/*
		@@ -5988,7 +5988,7 @@ int tcp_rcv_state_process(struct sock sk, struct sk_buff skb,
		goto discard;
		}

		if (!th->ack)
		if (!th->ack && !th->rst)
		goto discard;

		if (!tcp_validate_incoming(sk, skb, th, 0))

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