From: Kuniyuki Iwashima Date: Fri, 15 Jul 2022 17:17:53 +0000 (-0700) Subject: tcp: Fix data-races around sysctl_max_syn_backlog. X-Git-Tag: v6.1-rc5~858^2~20^2~2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=79539f34743d3e14cc1fa6577d326a82cc64d62f;p=platform%2Fkernel%2Flinux-starfive.git tcp: Fix data-races around sysctl_max_syn_backlog. While reading sysctl_max_syn_backlog, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") 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 de4ccd1..d451248 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6956,10 +6956,12 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, tcp_rsk(req)->ts_off = af_ops->init_ts_off(net, skb); if (!want_cookie && !isn) { + int max_syn_backlog = READ_ONCE(net->ipv4.sysctl_max_syn_backlog); + /* Kill the following clause, if you dislike this way. */ if (!syncookies && - (net->ipv4.sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) < - (net->ipv4.sysctl_max_syn_backlog >> 2)) && + (max_syn_backlog - inet_csk_reqsk_queue_len(sk) < + (max_syn_backlog >> 2)) && !tcp_peer_is_proven(req, dst)) { /* Without syncookies last quarter of * backlog is filled with destinations,