Commit 6cc566df authored Jul 18, 2022 by Kuniyuki Iwashima Committed by Greg Kroah-Hartman Jul 29, 2022

tcp: Fix a data-race around sysctl_tcp_stdurg.



[ Upstream commit 4e08ed41cb1194009fc1a916a59ce3ed4afd77cd ]

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

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
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 7f68bed1

net/ipv4/tcp_input.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -5356,7 +5356,7 @@ static void tcp_check_urg(struct sock sk, const struct tcphdr th)
		struct tcp_sock *tp = tcp_sk(sk);
		u32 ptr = ntohs(th->urg_ptr);

		if (ptr && !sock_net(sk)->ipv4.sysctl_tcp_stdurg)
		if (ptr && !READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_stdurg))
		ptr--;
		ptr += ntohl(th->seq);