tcp/dccp: Fix a data-race around sysctl_tcp_fwmark_accept.

[ 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>

diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index defd77baf74a64b032008f14474da8ba65cf4ed8..33344d54ad656c188fc341cb7a6f84834ee681e6 100644 (file)
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -107,7 +107,8 @@ 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;