ipv6: tcp: add rcu locking in tcp_v6_send_synack()
authorEric Dumazet <edumazet@google.com>
Fri, 8 Jan 2016 17:35:51 +0000 (09:35 -0800)
committerDavid S. Miller <davem@davemloft.net>
Mon, 11 Jan 2016 03:58:03 +0000 (22:58 -0500)
When first SYNACK is sent, we already hold rcu_read_lock(), but this
is not true if a SYNACK is retransmitted, as a timer (soft) interrupt
does not hold rcu_read_lock()

Fixes: 45f6fad84cc30 ("ipv6: add complete rcu protection around np->opt")
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv6/tcp_ipv6.c

index 6b8a8a9091fa113ee28906c570e78811e6f29815..bd100b47c7171ce1d85ea5a437c13081a60cd29c 100644 (file)
@@ -462,8 +462,10 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
                if (np->repflow && ireq->pktopts)
                        fl6->flowlabel = ip6_flowlabel(ipv6_hdr(ireq->pktopts));
 
+               rcu_read_lock();
                err = ip6_xmit(sk, skb, fl6, rcu_dereference(np->opt),
                               np->tclass);
+               rcu_read_unlock();
                err = net_xmit_eval(err);
        }