Commit 2ab2ddd3 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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



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: 1ad98e9d ("tcp/dccp: fix lockdep issue when SYN is backlogged")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ff58e2df

include/net/inet_sock.h

+0 −5
Original line number Original line Diff line number Diff line
@@ -130,11 +130,6 @@ static inline int inet_request_bound_dev_if(const struct sock *sk, 
	return sk->sk_bound_dev_if;

	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 {

struct inet_cork {

	unsigned int		flags;

	unsigned int		flags;

	__be32			addr;

	__be32			addr;

net/dccp/ipv4.c

+3 −1
Original line number Original line Diff line number Diff line
@@ -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,

		dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,

							      ireq->ir_rmt_addr);

							      ireq->ir_rmt_addr);

		rcu_read_lock();

		err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,

		err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,

					    ireq->ir_rmt_addr,

					    ireq->ir_rmt_addr,

					    ireq_opt_deref(ireq));

					    rcu_dereference(ireq->ireq_opt));

		rcu_read_unlock();

		err = net_xmit_eval(err);

		err = net_xmit_eval(err);

	}

	}

net/ipv4/inet_connection_sock.c

+4 −1
Original line number Original line Diff line number Diff line
@@ -544,7 +544,8 @@ struct dst_entry *inet_csk_route_req(const struct sock *sk, 
	struct ip_options_rcu *opt;

	struct ip_options_rcu *opt;

	struct rtable *rt;

	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,

	flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,

			   RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,

			   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;

		goto no_route;

	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)

	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)

		goto route_err;

		goto route_err;

	rcu_read_unlock();

	return &rt->dst;

	return &rt->dst;





route_err:

route_err:

	ip_rt_put(rt);

	ip_rt_put(rt);

no_route:

no_route:

	rcu_read_unlock();

	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);

	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);

	return NULL;

	return NULL;

}

}

net/ipv4/tcp_ipv4.c

+3 −1
Original line number Original line Diff line number Diff line
@@ -943,9 +943,11 @@ static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst, 
	if (skb) {

	if (skb) {

		__tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr);

		__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,

		err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,

					    ireq->ir_rmt_addr,

					    ireq->ir_rmt_addr,

					    ireq_opt_deref(ireq));

					    rcu_dereference(ireq->ireq_opt));

		rcu_read_unlock();

		err = net_xmit_eval(err);

		err = net_xmit_eval(err);

	}

	}

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