From 2ab2ddd301a22ca3c5f0b743593e4ad2953dfa53 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 2 Oct 2018 12:35:05 -0700 Subject: 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: 1ad98e9d1bdf ("tcp/dccp: fix lockdep issue when SYN is backlogged") Signed-off-by: Eric Dumazet Reported-by: Willem de Bruijn Signed-off-by: David S. Miller --- net/dccp/ipv4.c | 4 +++- net/ipv4/inet_connection_sock.c | 5 ++++- net/ipv4/tcp_ipv4.c | 4 +++- 3 files changed, 10 insertions(+), 3 deletions(-) (limited to 'net') diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index b08feb219b44..8e08cea6f178 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -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); } diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index dfd5009f96ef..15e7f7915a21 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -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; } diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 44c09eddbb78..cd426313a298 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -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); } -- cgit v1.2.3-59-g8ed1b