Commit 51bd690f authored Jan 08, 2016 by Eric Dumazet Committed by Sasha Levin Feb 15, 2016

ipv6: tcp: add rcu locking in tcp_v6_send_synack()



[ Upstream commit 3e4006f0b86a5ae5eb0e8215f9a9e1db24506977 ]

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>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

parent ea06dfa2

net/ipv6/tcp_ipv6.c

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -502,8 +502,10 @@ static int tcp_v6_send_synack(struct sock sk, struct dst_entry dst,
	fl6->flowlabel = ip6_flowlabel(ipv6_hdr(ireq->pktopts));		fl6->flowlabel = ip6_flowlabel(ipv6_hdr(ireq->pktopts));

	skb_set_queue_mapping(skb, queue_mapping);		skb_set_queue_mapping(skb, queue_mapping);
			rcu_read_lock();
	err = ip6_xmit(sk, skb, fl6, rcu_dereference(np->opt),		err = ip6_xmit(sk, skb, fl6, rcu_dereference(np->opt),
	np->tclass);		np->tclass);
			rcu_read_unlock();
	err = net_xmit_eval(err);		err = net_xmit_eval(err);
	}		}