tcp: Fix a data-race around sysctl_tcp_invalid_ratelimit.

While reading sysctl_tcp_invalid_ratelimit, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 032ee42 ("tcp: helpers to mitigate ACK loops by rate-limiting out-of-window dupacks") Signed-off-by: Kuniyuki Iwashima <[email protected]> Signed-off-by: David S. Miller <[email protected]>
majek · Jul 22, 2022 · 2afdbe7 · 2afdbe7
1 parent 85225e6
commit 2afdbe7
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
@@ -3581,7 +3581,8 @@ static bool __tcp_oow_rate_limited(struct net *net, int mib_idx,
 	if (*last_oow_ack_time) {
 		s32 elapsed = (s32)(tcp_jiffies32 - *last_oow_ack_time);
 
-		if (0 <= elapsed && elapsed < net->ipv4.sysctl_tcp_invalid_ratelimit) {
+		if (0 <= elapsed &&
+		    elapsed < READ_ONCE(net->ipv4.sysctl_tcp_invalid_ratelimit)) {
 			NET_INC_STATS(net, mib_idx);
 			return true;	/* rate-limited: don't send yet! */
 		}