diff options
author | Eric Dumazet <edumazet@google.com> | 2015-03-24 15:58:52 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2015-03-24 21:16:29 -0400 |
commit | 80f03e27a309f3e32ebdd9629ac0320005a2180b (patch) | |
tree | 4516faa5da144dde9c1cd899ae3d99090e3852db /net | |
parent | 9ead3527f5967440f2ff57fd2fa25dd0e460fc5a (diff) | |
download | linux-80f03e27a309f3e32ebdd9629ac0320005a2180b.tar.gz linux-80f03e27a309f3e32ebdd9629ac0320005a2180b.tar.bz2 linux-80f03e27a309f3e32ebdd9629ac0320005a2180b.zip |
tcp: md5: fix rcu lockdep splat
While timer handler effectively runs a rcu read locked section,
there is no explicit rcu_read_lock()/rcu_read_unlock() annotations
and lockdep can be confused here :
net/ipv4/tcp_ipv4.c-906- /* caller either holds rcu_read_lock() or socket lock */
net/ipv4/tcp_ipv4.c:907: md5sig = rcu_dereference_check(tp->md5sig_info,
net/ipv4/tcp_ipv4.c-908- sock_owned_by_user(sk) ||
net/ipv4/tcp_ipv4.c-909- lockdep_is_held(&sk->sk_lock.slock));
Let's explicitely acquire rcu_read_lock() in tcp_make_synack()
Before commit fa76ce7328b ("inet: get rid of central tcp/dccp listener
timer"), we were holding listener lock so lockdep was happy.
Fixes: fa76ce7328b ("inet: get rid of central tcp/dccp listener timer")
Signed-off-by: Eric DUmazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r-- | net/ipv4/tcp_output.c | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 18474088c3d0..5b7fad4b314c 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -601,15 +601,14 @@ static unsigned int tcp_synack_options(struct sock *sk, struct request_sock *req, unsigned int mss, struct sk_buff *skb, struct tcp_out_options *opts, - struct tcp_md5sig_key **md5, + const struct tcp_md5sig_key *md5, struct tcp_fastopen_cookie *foc) { struct inet_request_sock *ireq = inet_rsk(req); unsigned int remaining = MAX_TCP_OPTION_SPACE; #ifdef CONFIG_TCP_MD5SIG - *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); - if (*md5) { + if (md5) { opts->options |= OPTION_MD5; remaining -= TCPOLEN_MD5SIG_ALIGNED; @@ -620,8 +619,6 @@ static unsigned int tcp_synack_options(struct sock *sk, */ ireq->tstamp_ok &= !ireq->sack_ok; } -#else - *md5 = NULL; #endif /* We always send an MSS option. */ @@ -2913,7 +2910,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, struct tcp_sock *tp = tcp_sk(sk); struct tcphdr *th; struct sk_buff *skb; - struct tcp_md5sig_key *md5; + struct tcp_md5sig_key *md5 = NULL; int tcp_header_size; int mss; @@ -2938,7 +2935,12 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, else #endif skb_mstamp_get(&skb->skb_mstamp); - tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, &md5, + +#ifdef CONFIG_TCP_MD5SIG + rcu_read_lock(); + md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); +#endif + tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5, foc) + sizeof(*th); skb_push(skb, tcp_header_size); @@ -2969,10 +2971,10 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, #ifdef CONFIG_TCP_MD5SIG /* Okay, we have all we need - do the md5 hash if needed */ - if (md5) { + if (md5) tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, md5, NULL, req, skb); - } + rcu_read_unlock(); #endif return skb; |