From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed, 13 Jul 2022 20:51:57 +0000 (-0700)
Subject: ip: Fix a data-race around sysctl_fwmark_reflect.
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=dccf8a67f30e18980d13f07006e5a536bbd1e136;p=linux.git

ip: Fix a data-race around sysctl_fwmark_reflect.

[ Upstream commit 85d0b4dbd74b95cc492b1f4e34497d3f894f5d9a ]

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

Fixes: e110861f8609 ("net: add a sysctl to reflect the fwmark on replies")
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/include/net/ip.h b/include/net/ip.h
index c69dd114f367b..a0ac57af82dcf 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -379,7 +379,7 @@ void ipfrag_init(void);
 void ip_static_sysctl_init(void);
 
 #define IP4_REPLY_MARK(net, mark) \
-	((net)->ipv4.sysctl_fwmark_reflect ? (mark) : 0)
+	(READ_ONCE((net)->ipv4.sysctl_fwmark_reflect) ? (mark) : 0)
 
 static inline bool ip_is_fragment(const struct iphdr *iph)
 {