evie/android_kernel_oneplus_msm8998
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tcp: md5: fix rcu lockdep splat

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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 fa76ce7328 ("inet: get rid of central tcp/dccp listener
timer"), we were holding listener lock so lockdep was happy.

Fixes: fa76ce7328 ("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>
This commit is contained in:
Eric Dumazet 2015-03-24 15:58:52 -07:00 • committed by David S. Miller
parent 9ead3527f5
commit 80f03e27a3
1 changed files with 11 additions and 9 deletions
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20
net/ipv4/tcp_output.c
View file

@ -601,15 +601,14 @@ static unsigned int tcp_synack_options(struct sock *sk,
struct request_sock *req, struct request_sock *req,
unsigned int mss, struct sk_buff *skb, unsigned int mss, struct sk_buff *skb,
struct tcp_out_options *opts, struct tcp_out_options *opts,
struct tcp_md5sig_key **md5, const struct tcp_md5sig_key *md5,
struct tcp_fastopen_cookie *foc) struct tcp_fastopen_cookie *foc)
{ {
struct inet_request_sock *ireq = inet_rsk(req); struct inet_request_sock *ireq = inet_rsk(req);
unsigned int remaining = MAX_TCP_OPTION_SPACE; unsigned int remaining = MAX_TCP_OPTION_SPACE;
#ifdef CONFIG_TCP_MD5SIG #ifdef CONFIG_TCP_MD5SIG
*md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); if (md5) {
if (*md5) {
opts->options |= OPTION_MD5; opts->options |= OPTION_MD5;
remaining -= TCPOLEN_MD5SIG_ALIGNED; remaining -= TCPOLEN_MD5SIG_ALIGNED;
@ -620,8 +619,6 @@ static unsigned int tcp_synack_options(struct sock *sk,
*/ */
ireq->tstamp_ok &= !ireq->sack_ok; ireq->tstamp_ok &= !ireq->sack_ok;
} }
#else
*md5 = NULL;
#endif #endif
/* We always send an MSS option. */ /* 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 tcp_sock *tp = tcp_sk(sk);
struct tcphdr *th; struct tcphdr *th;
struct sk_buff *skb; struct sk_buff *skb;
struct tcp_md5sig_key *md5; struct tcp_md5sig_key *md5 = NULL;
int tcp_header_size; int tcp_header_size;
int mss; int mss;
@ -2938,7 +2935,12 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
else else
#endif #endif
skb_mstamp_get(&skb->skb_mstamp); 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); foc) + sizeof(*th);
skb_push(skb, tcp_header_size); 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 #ifdef CONFIG_TCP_MD5SIG
/* Okay, we have all we need - do the md5 hash if needed */ /* 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, tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location,
md5, NULL, req, skb); md5, NULL, req, skb);
} rcu_read_unlock();
#endif #endif
return skb; return skb;