4.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ 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: Eric Dumazet edumazet@google.com Reported-by: soukjin bae soukjin.bae@samsung.com Acked-by: Neal Cardwell ncardwell@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/tcp.h | 1 + net/ipv4/tcp.c | 1 - 2 files changed, 1 insertion(+), 1 deletion(-)
--- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1457,6 +1457,7 @@ static inline void tcp_write_queue_purge sk_wmem_free_skb(sk, skb); sk_mem_reclaim(sk); tcp_clear_all_retrans_hints(tcp_sk(sk)); + inet_csk(sk)->icsk_backoff = 0; }
static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2253,7 +2253,6 @@ int tcp_disconnect(struct sock *sk, int 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->packets_out = 0;