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Commit 3e4006f0 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv6: tcp: add rcu locking in tcp_v6_send_synack() 



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: 45f6fad8 ("ipv6: add complete rcu protection around np->opt")
Reported-by: default avatarDave Jones <davej@codemonkey.org.uk>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 320f1a4a

net/ipv6/tcp_ipv6.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

	}