[PATCH 4.19 23/56] net: Fix a data-race around sysctl_net_busy_poll.

Greg Kroah-Hartman
2022-09-02T12:51:37Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit c42b7cddea47503411bfb5f2f93a4154aaffa2d9 ]

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

Fixes: 060212928670 ("net: add low latency socket poll")
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>
---
include/net/busy_poll.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h
index c76a5e9894dac..8f42f6f3af86f 100644
--- a/include/net/busy_poll.h
+++ b/include/net/busy_poll.h
@@ -43,7 +43,7 @@ extern unsigned int sysctl_net_busy_poll __read_mostly;

static inline bool net_busy_loop_on(void)
{
- return sysctl_net_busy_poll;
+ return READ_ONCE(sysctl_net_busy_poll);
}

static inline bool sk_can_busy_loop(const struct sock *sk)
--
2.35.1