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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kuniyuki Iwashima <kuniyu@amazon.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 18/87] ip: Fix data-races around sysctl_ip_nonlocal_bind.
Date:   Wed, 27 Jul 2022 18:10:11 +0200
Message-Id: <20220727161009.757058892@linuxfoundation.org>
In-Reply-To: <20220727161008.993711844@linuxfoundation.org>
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From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 289d3b21fb0bfc94c4e98f10635bba1824e5f83c ]

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

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>
---
 include/net/inet_sock.h | 2 +-
 net/sctp/protocol.c     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 34c4436fd18f..40f92f5a3047 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -375,7 +375,7 @@ static inline bool inet_get_convert_csum(struct sock *sk)
 static inline bool inet_can_nonlocal_bind(struct net *net,
 					  struct inet_sock *inet)
 {
-	return net->ipv4.sysctl_ip_nonlocal_bind ||
+	return READ_ONCE(net->ipv4.sysctl_ip_nonlocal_bind) ||
 		inet->freebind || inet->transparent;
 }
 
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index bb370a7948f4..363a64c12414 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -358,7 +358,7 @@ static int sctp_v4_available(union sctp_addr *addr, struct sctp_sock *sp)
 	if (addr->v4.sin_addr.s_addr != htonl(INADDR_ANY) &&
 	   ret != RTN_LOCAL &&
 	   !sp->inet.freebind &&
-	   !net->ipv4.sysctl_ip_nonlocal_bind)
+	    !READ_ONCE(net->ipv4.sysctl_ip_nonlocal_bind))
 		return 0;
 
 	if (ipv6_only_sock(sctp_opt2sk(sp)))
-- 
2.35.1