[PATCH 4.19 24/56] net: Fix a data-race around sysctl_net_busy_read.

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ 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>
---
 net/core/sock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 79f085df52cef..cd23a8e4556ca 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2856,7 +2856,7 @@ 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 = ~0U;
-- 
2.35.1