[PATCH 4.19 09/62] ip: Fix a data-race around sysctl_fwmark_reflect.

From: Greg Kroah-Hartman
Date: Wed Jul 27 2022 - 12:31:56 EST


From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
include/net/ip.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/ip.h b/include/net/ip.h
index 471463bfe6f9..0f820e68bd8f 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -341,7 +341,7 @@ 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)
{
--
2.35.1