From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed, 20 Jul 2022 16:50:26 +0000 (-0700)
Subject: tcp: Fix a data-race around sysctl_tcp_invalid_ratelimit.
X-Git-Tag: v5.15.73~1866
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=dac5644a823ef52d5abdeb3db88d49e98e4a0f29;p=platform%2Fkernel%2Flinux-rpi.git

tcp: Fix a data-race around sysctl_tcp_invalid_ratelimit.

[ Upstream commit 2afdbe7b8de84c28e219073a6661080e1b3ded48 ]

While reading sysctl_tcp_invalid_ratelimit, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its reader.

Fixes: 032ee4236954 ("tcp: helpers to mitigate ACK loops by rate-limiting out-of-window dupacks")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b925c76..018be3f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3574,7 +3574,8 @@ 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! */
 		}