From 55be873695ed8912eb77ff46d1d1cadf028bd0f3 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Fri, 15 Jul 2022 10:17:51 -0700 Subject: [PATCH] tcp: Fix a data-race around sysctl_tcp_notsent_lowat. While reading sysctl_tcp_notsent_lowat, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: c9bee3b7fdec ("tcp: TCP_NOTSENT_LOWAT socket option") Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller --- include/net/tcp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 23ccaa386746..6ee1fb4fb292 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -2027,7 +2027,7 @@ void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) { struct net *net = sock_net((struct sock *)tp); - return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; + return tp->notsent_lowat ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat); } bool tcp_stream_memory_free(const struct sock *sk, int wake); -- 2.20.1