net: Fix a data-race around sysctl_net_busy_read.

[ Upstream commit e59ef36f0795696ab229569c153936bfd068d21c ]

While reading sysctl_net_busy_read, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 2d48d67fa8cd ("net: poll/select low latency socket support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/core/sock.c b/net/core/sock.c
index d672e63a5c2d4f0b911ddc5dd206bdbd2bbbad45..16ab5ef749c6046bb8b9dada0d4b412736b53615 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3365,7 +3365,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)
 
 #ifdef CONFIG_NET_RX_BUSY_POLL
        sk->sk_napi_id          =       0;
-       sk->sk_ll_usec          =       sysctl_net_busy_read;
+       sk->sk_ll_usec          =       READ_ONCE(sysctl_net_busy_read);
 #endif
 
        sk->sk_max_pacing_rate = ~0UL;