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inet: make sure to grab rcu_read_lock before using ireq->ireq_opt

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Timer handlers do not imply rcu_read_lock(), so my recent fix
triggered a LOCKDEP warning when SYNACK is retransmit.

Lets add rcu_read_lock()/rcu_read_unlock() pairs around ireq->ireq_opt
usages instead of guessing what is done by callers, since it is
not worth the pain.

Get rid of ireq_opt_deref() helper since it hides the logic
without real benefit, since it is now a standard rcu_dereference().

Fixes: 1ad98e9d1b ("tcp/dccp: fix lockdep issue when SYN is backlogged")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2018-10-02 12:35:05 -07:00 committed by David S. Miller
parent ff58e2df62
commit 2ab2ddd301
4 changed files with 10 additions and 8 deletions
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5
include/net/inet_sock.h
View File

@ -130,11 +130,6 @@ static inline int inet_request_bound_dev_if(const struct sock *sk,
return sk->sk_bound_dev_if;
}
static inline struct ip_options_rcu *ireq_opt_deref(const struct inet_request_sock *ireq)
{
return rcu_dereference(ireq->ireq_opt);
}
struct inet_cork {
unsigned int flags;
__be32 addr;

4
net/dccp/ipv4.c
View File

@ -493,9 +493,11 @@ static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req
dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
ireq->ir_rmt_addr);
rcu_read_lock();
err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
ireq->ir_rmt_addr,
ireq_opt_deref(ireq));
rcu_dereference(ireq->ireq_opt));
rcu_read_unlock();
err = net_xmit_eval(err);
}

5
net/ipv4/inet_connection_sock.c
View File

@ -544,7 +544,8 @@ struct dst_entry *inet_csk_route_req(const struct sock *sk,
struct ip_options_rcu *opt;
struct rtable *rt;
opt = ireq_opt_deref(ireq);
rcu_read_lock();
opt = rcu_dereference(ireq->ireq_opt);
flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
@ -558,11 +559,13 @@ struct dst_entry *inet_csk_route_req(const struct sock *sk,
goto no_route;
if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
goto route_err;
rcu_read_unlock();
return &rt->dst;
route_err:
ip_rt_put(rt);
no_route:
rcu_read_unlock();
__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
return NULL;
}

4
net/ipv4/tcp_ipv4.c
View File

@ -943,9 +943,11 @@ static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
if (skb) {
__tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr);
rcu_read_lock();
err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
ireq->ir_rmt_addr,
ireq_opt_deref(ireq));
rcu_dereference(ireq->ireq_opt));
rcu_read_unlock();
err = net_xmit_eval(err);
}