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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 5.18 116/231] icmp: Fix a data-race around sysctl_icmp_errors_use_inbound_ifaddr.
Date:   Tue, 19 Jul 2022 13:53:21 +0200
Message-Id: <20220719114724.257227943@linuxfoundation.org>
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From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit d2efabce81db7eed1c98fa1a3f203f0edd738ac3 ]

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

Fixes: 1c2fb7f93cb2 ("[IPV4]: Sysctl configurable icmp error source address.")
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>
---
 net/ipv4/icmp.c            | 2 +-
 net/ipv4/sysctl_net_ipv4.c | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 1a061d10949f..37ba5f042908 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -693,7 +693,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
 
 		rcu_read_lock();
 		if (rt_is_input_route(rt) &&
-		    net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
+		    READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr))
 			dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 
 		if (dev)
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 4cf2a6f560d4..33e65e79e46e 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -639,6 +639,8 @@ static struct ctl_table ipv4_net_table[] = {
 		.maxlen		= sizeof(u8),
 		.mode		= 0644,
 		.proc_handler	= proc_dou8vec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE
 	},
 	{
 		.procname	= "icmp_ratelimit",
-- 
2.35.1