tcp: Fix data-races around sysctl_tcp_syn(ack)?_retries.

While reading sysctl_tcp_syn(ack)?_retries, they can be changed
concurrently.  Thus, we need to add READ_ONCE() to their readers.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kuniyuki Iwashima
2022-07-15 10:17:46 -07:00
committed by David S. Miller
parent f2f316e287
commit 20a3b1c0f6
3 changed files with 11 additions and 5 deletions

View File

@@ -239,7 +239,8 @@ static int tcp_write_timeout(struct sock *sk)
if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
if (icsk->icsk_retransmits)
__dst_negative_advice(sk);
retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
retry_until = icsk->icsk_syn_retries ? :
READ_ONCE(net->ipv4.sysctl_tcp_syn_retries);
expired = icsk->icsk_retransmits >= retry_until;
} else {
if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1, 0)) {
@@ -406,12 +407,15 @@ abort: tcp_write_err(sk);
static void tcp_fastopen_synack_timer(struct sock *sk, struct request_sock *req)
{
struct inet_connection_sock *icsk = inet_csk(sk);
int max_retries = icsk->icsk_syn_retries ? :
sock_net(sk)->ipv4.sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */
struct tcp_sock *tp = tcp_sk(sk);
int max_retries;
req->rsk_ops->syn_ack_timeout(req);
/* add one more retry for fastopen */
max_retries = icsk->icsk_syn_retries ? :
READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_synack_retries) + 1;
if (req->num_timeout >= max_retries) {
tcp_write_err(sk);
return;