linux-kernel - [PATCH 5.18 111/231] tcp: Fix a data-race around sysctl_max_tw

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Message-Id: <20220719114723.910459435@linuxfoundation.org>
Date:   Tue, 19 Jul 2022 13:53:16 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kuniyuki Iwashima <kuniyu@...zon.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.18 111/231] tcp: Fix a data-race around sysctl_max_tw_buckets.

From: Kuniyuki Iwashima <kuniyu@...zon.com>

[ Upstream commit 6f605b57f3782114e330e108ce1903ede22ec675 ]

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

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/ipv4/inet_timewait_sock.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 0ec501845cb3..47ccc343c9fb 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -156,7 +156,8 @@ struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,
 {
 	struct inet_timewait_sock *tw;
 
-	if (refcount_read(&dr->tw_refcount) - 1 >= dr->sysctl_max_tw_buckets)
+	if (refcount_read(&dr->tw_refcount) - 1 >=
+	    READ_ONCE(dr->sysctl_max_tw_buckets))
 		return NULL;
 
 	tw = kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab,
-- 
2.35.1