[PATCH 4.14 06/37] tcp/dccp: Fix a data-race around sysctl_tcp_fwmark_accept.

Greg Kroah-Hartman
2022-07-27T16:25:36Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 1a0008f9df59451d0a17806c1ee1a19857032fa8 ]

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

Fixes: 84f39b08d786 ("net: support marking accepting TCP sockets")
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 | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 16a1492a5bd3..f279d72273f6 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -110,7 +110,8 @@ static inline struct inet_request_sock *inet_rsk(const struct request_sock *sk)

static inline u32 inet_request_mark(const struct sock *sk, struct sk_buff *skb)
{
- if (!sk->sk_mark && sock_net(sk)->ipv4.sysctl_tcp_fwmark_accept)
+ if (!sk->sk_mark &&
+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fwmark_accept))
return skb->mark;

return sk->sk_mark;
--
2.35.1