[PATCH 5.15 36/69] tcp: Fix a data-race around sysctl_tcp_min_tso_segs.

Greg Kroah-Hartman
2022-08-01T12:04:00Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit e0bb4ab9dfddd872622239f49fb2bd403b70853b ]

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

Fixes: 95bd09eb2750 ("tcp: TSO packets automatic sizing")
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/ipv4/tcp_output.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1986,7 +1986,7 @@ static u32 tcp_tso_segs(struct sock *sk,

min_tso = ca_ops->min_tso_segs ?
ca_ops->min_tso_segs(sk) :
- sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs;
+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs);

tso_segs = tcp_tso_autosize(sk, mss_now, min_tso);
return min_t(u32, tso_segs, sk->sk_gso_max_segs);