Commit e9362a99 authored Jul 15, 2022 by Kuniyuki Iwashima Committed by Greg Kroah-Hartman Jul 29, 2022

tcp: Fix a data-race around sysctl_tcp_notsent_lowat.



[ 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: c9bee3b7 ("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>

parent b0d9f04c

include/net/tcp.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -1947,7 +1947,7 @@ 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);
		}

		/* @wake is one when sk_stream_write_space() calls us.