From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed, 6 Jul 2022 23:39:58 +0000 (-0700)
Subject: tcp: Fix a data-race around sysctl_tcp_max_orphans.
X-Git-Tag: v5.10.132~65
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=6481a8a72a746dc96e3aa70a9f9f6d3daf0f88c2;p=users%2Fdwmw2%2Flinux.git

tcp: Fix a data-race around sysctl_tcp_max_orphans.

[ Upstream commit 47e6ab24e8c6e3ca10ceb5835413f401f90de4bf ]

While reading sysctl_tcp_max_orphans, it can be changed concurrently.
So, we need to add READ_ONCE() to avoid a data-race.

Fixes: 1da177e4c3f4 ("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>
---

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index a3ec2a08027b8..19c13ad5c121b 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2490,7 +2490,8 @@ static void tcp_orphan_update(struct timer_list *unused)
 
 static bool tcp_too_many_orphans(int shift)
 {
-	return READ_ONCE(tcp_orphan_cache) << shift > sysctl_tcp_max_orphans;
+	return READ_ONCE(tcp_orphan_cache) << shift >
+		READ_ONCE(sysctl_tcp_max_orphans);
 }
 
 bool tcp_check_oom(struct sock *sk, int shift)