From: Kuniyuki Iwashima Date: Wed, 20 Jul 2022 16:50:21 +0000 (-0700) Subject: tcp: Fix a data-race around sysctl_tcp_challenge_ack_limit. X-Git-Tag: howlett/maple/20220816~308^2~32^2~5 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=db3815a2fa691da145cfbe834584f31ad75df9ff;p=users%2Fjedix%2Flinux-maple.git tcp: Fix a data-race around sysctl_tcp_challenge_ack_limit. While reading sysctl_tcp_challenge_ack_limit, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 282f23c6ee34 ("tcp: implement RFC 5961 3.2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller --- diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index debfff94f3af..d386a69b1c05 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3629,7 +3629,7 @@ static void tcp_send_challenge_ack(struct sock *sk) /* Then check host-wide RFC 5961 rate limit. */ now = jiffies / HZ; if (now != challenge_timestamp) { - u32 ack_limit = net->ipv4.sysctl_tcp_challenge_ack_limit; + u32 ack_limit = READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit); u32 half = (ack_limit + 1) >> 1; challenge_timestamp = now;