This is a note to let you know that I've just added the patch titled
tcp: Fix a data-race around sysctl_tcp_challenge_ack_limit.
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tcp-fix-a-data-race-around-sysctl_tcp_challenge_ack_.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 820771349c258fcb893ad8ff9992b0cc1d27de45
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Wed Jul 20 09:50:21 2022 -0700
tcp: Fix a data-race around sysctl_tcp_challenge_ack_limit.
[ Upstream commit db3815a2fa691da145cfbe834584f31ad75df9ff ]
While reading sysctl_tcp_challenge_ack_limit, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its reader.
Fixes: 282f23c6ee34 ("tcp: implement RFC 5961 3.2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 426f8fe02850..a5357ebfbcc0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3622,7 +3622,7 @@ static void tcp_send_challenge_ack(struct sock *sk, const struct sk_buff *skb)
/* Then check host-wide RFC 5961 rate limit. */
now = jiffies / HZ;
if (now != challenge_timestamp) {
- u32 ack_limit = net->ipv4.sysctl_tcp_challenge_ack_limit;
+ u32 ack_limit = READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit);
u32 half = (ack_limit + 1) >> 1;
challenge_timestamp = now;
