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Commit 3a493b76 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
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tcp: clear icsk_backoff in tcp_write_queue_purge() 



[ Upstream commit 04c03114be82194d4a4858d41dba8e286ad1787c ]

soukjin bae reported a crash in tcp_v4_err() handling
ICMP_DEST_UNREACH after tcp_write_queue_head(sk)
returned a NULL pointer.

Current logic should have prevented this :

  if (seq != tp->snd_una  || !icsk->icsk_retransmits ||
      !icsk->icsk_backoff || fastopen)
      break;

Problem is the write queue might have been purged
and icsk_backoff has not been cleared.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarsoukjin bae <soukjin.bae@samsung.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 859838ff

include/net/tcp.h

+1 −0
Original line number Diff line number Diff line
@@ -1622,6 +1622,7 @@ static inline void tcp_write_queue_purge(struct sock *sk) 
	tcp_clear_all_retrans_hints(tcp_sk(sk));

	tcp_init_send_head(sk);

	tcp_sk(sk)->packets_out = 0;

	inet_csk(sk)->icsk_backoff = 0;

}



static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)

net/ipv4/tcp.c

+0 −1
Original line number Diff line number Diff line
@@ -2347,7 +2347,6 @@ int tcp_disconnect(struct sock *sk, int flags) 
	tp->write_seq += tp->max_window + 2;

	if (tp->write_seq == 0)

		tp->write_seq = 1;

	icsk->icsk_backoff = 0;

	tp->snd_cwnd = 2;

	icsk->icsk_probes_out = 0;

	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;