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: c9bee3b ("tcp: TCP_NOTSENT_LOWAT socket option") Signed-off-by: Kuniyuki Iwashima <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
somestupidgirl · Jan 29, 2025 · a3de4b5 · a3de4b5
1 parent c11c6a5
commit a3de4b5
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/include/net/tcp.h b/include/net/tcp.h
@@ -2007,7 +2007,7 @@ 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)