write in 30M

hc

2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc

 kernel/net/ipv4/tcp_minisocks.c
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..
@@ -523,7 +523,7 @@
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 	newtp->max_window = newtp->snd_wnd;
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 	if (newtp->rx_opt.tstamp_ok) {
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-		newtp->rx_opt.ts_recent = req->ts_recent;
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+		newtp->rx_opt.ts_recent = READ_ONCE(req->ts_recent);
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 		newtp->rx_opt.ts_recent_stamp = ktime_get_seconds();
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 		newtp->tcp_header_len = sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED;
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 	} else {
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@@ -565,6 +565,9 @@
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  * validation and inside tcp_v4_reqsk_send_ack(). Can we do better?
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  *
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  * We don't need to initialize tmp_opt.sack_ok as we don't use the results
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+ *
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+ * Note: If @fastopen is true, this can be called from process context.
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+ *       Otherwise, this is from BH context.
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  */
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 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
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@@ -583,7 +586,7 @@
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 		tcp_parse_options(sock_net(sk), skb, &tmp_opt, 0, NULL);
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 		if (tmp_opt.saw_tstamp) {
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-			tmp_opt.ts_recent = req->ts_recent;
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+			tmp_opt.ts_recent = READ_ONCE(req->ts_recent);
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 			if (tmp_opt.rcv_tsecr)
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 				tmp_opt.rcv_tsecr -= tcp_rsk(req)->ts_off;
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 			/* We do not store true stamp, but it is not required,
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@@ -717,14 +720,17 @@
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 					  &tcp_rsk(req)->last_oow_ack_time))
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 			req->rsk_ops->send_ack(sk, skb, req);
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 		if (paws_reject)
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-			__NET_INC_STATS(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED);
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+			NET_INC_STATS(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED);
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 		return NULL;
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 	}
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 	/* In sequence, PAWS is OK. */
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+	/* TODO: We probably should defer ts_recent change once
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+	 * we take ownership of @req.
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+	 */
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 	if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_nxt))
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-		req->ts_recent = tmp_opt.rcv_tsval;
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+		WRITE_ONCE(req->ts_recent, tmp_opt.rcv_tsval);
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 	if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) {
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 		/* Truncate SYN, it is out of window starting
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@@ -736,7 +742,7 @@
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 	 *	   "fourth, check the SYN bit"
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 	 */
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 	if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN)) {
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-		__TCP_INC_STATS(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
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+		TCP_INC_STATS(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
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 		goto embryonic_reset;
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 	}
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