From c31484b011f95de4739dd41f4bcdfb06f51f9c05 Mon Sep 17 00:00:00 2001
From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed, 7 Sep 2022 09:24:11 +0000
Subject: [PATCH] tcp: Fix a data-race around sysctl_tcp_notsent_lowat.
stable inclusion
from stable-v4.19.254
commit 0f75343584ee474303e17efe0610bdd170af1d13
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5Q0SQ
CVE: NA
--------------------------------
[ Upstream commit 55be873695ed8912eb77ff46d1d1cadf028bd0f3 ]
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 <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>
---
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 970f4a70e03c..d633f98b40f9 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1878,7 +1878,7 @@ 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);
}
static inline bool tcp_stream_memory_free(const struct sock *sk)
--
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