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authorEric Dumazet <edumazet@google.com>2018-10-02 12:35:05 -0700
committerDavid S. Miller <davem@davemloft.net>2018-10-02 15:52:12 -0700
commit2ab2ddd301a22ca3c5f0b743593e4ad2953dfa53 (patch)
tree3ec72a50a6be78a4bc8eb73d8c9bd14df798aa26
parentnfp: avoid soft lockups under control message storm (diff)
downloadlinux-dev-2ab2ddd301a22ca3c5f0b743593e4ad2953dfa53.tar.xz
linux-dev-2ab2ddd301a22ca3c5f0b743593e4ad2953dfa53.zip
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 <edumazet@google.com> Reported-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/inet_sock.h5
-rw-r--r--net/dccp/ipv4.c4
-rw-r--r--net/ipv4/inet_connection_sock.c5
-rw-r--r--net/ipv4/tcp_ipv4.c4
4 files changed, 10 insertions, 8 deletions
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index a8cd5cf9ff5b..a80fd0ac4563 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -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;
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);
}