From: Kuniyuki Iwashima Date: Tue, 12 Jul 2022 00:15:31 +0000 (-0700) Subject: tcp: Fix a data-race around sysctl_tcp_ecn_fallback. X-Git-Tag: howlett/maple/20220816~379^2~17^2~2 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=12b8d9ca7e678abc48195294494f1815b555d658;p=users%2Fjedix%2Flinux-maple.git tcp: Fix a data-race around sysctl_tcp_ecn_fallback. While reading sysctl_tcp_ecn_fallback, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 492135557dc0 ("tcp: add rfc3168, section 6.1.1.1. fallback") Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller --- diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 5e308c1715af..108fd86f2718 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -685,6 +685,8 @@ static struct ctl_table ipv4_net_table[] = { .maxlen = sizeof(u8), .mode = 0644, .proc_handler = proc_dou8vec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, }, { .procname = "ip_dynaddr", diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 3dc17551ce25..11aa0ab10bba 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -346,7 +346,7 @@ static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) { - if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback) + if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback)) /* tp->ecn_flags are cleared at a later point in time when * SYN ACK is ultimatively being received. */