From: John Fastabend <john.fastabend@gmail.com>
Date: Mon, 28 Aug 2017 07:10:45 -0700
Subject: bpf: sockmap add missing rcu_read_(un)lock in smap_data_ready
Patch-mainline: v4.14-rc1
Git-commit: d26e597d87635d90128fafb3f6bb0a14d972d952
References: bsc#1109837

References to psock must be done inside RCU critical section.

Fixes: 174a79ff9515 ("bpf: sockmap with sk redirect support")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 kernel/bpf/sockmap.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -227,11 +227,14 @@ static void smap_data_ready(struct sock
 {
 	struct smap_psock *psock;
 
-	write_lock_bh(&sk->sk_callback_lock);
+	rcu_read_lock();
 	psock = smap_psock_sk(sk);
-	if (likely(psock))
+	if (likely(psock)) {
+		write_lock_bh(&sk->sk_callback_lock);
 		strp_data_ready(&psock->strp);
-	write_unlock_bh(&sk->sk_callback_lock);
+		write_unlock_bh(&sk->sk_callback_lock);
+	}
+	rcu_read_unlock();
 }
 
 static void smap_tx_work(struct work_struct *w)