This is a note to let you know that I've just added the patch titled
tcp: Fix a data-race around sysctl_tcp_comp_sack_nr.
to the 4.19-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_comp_sack_nr.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 75b97c52f2924b2070dd124273d2eca10079d907
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Fri Jul 22 11:22:03 2022 -0700
tcp: Fix a data-race around sysctl_tcp_comp_sack_nr.
[ Upstream commit 79f55473bfc8ac51bd6572929a679eeb4da22251 ]
While reading sysctl_tcp_comp_sack_nr, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.
Fixes: 9c21d2fc41c0 ("tcp: add tcp_comp_sack_nr sysctl")
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 b71866aba426..e1d065ea5a15 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5239,7 +5239,7 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible)
}
if (!tcp_is_sack(tp) ||
- tp->compressed_ack >= sock_net(sk)->ipv4.sysctl_tcp_comp_sack_nr)
+ tp->compressed_ack >= READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_comp_sack_nr))
goto send_now;
if (tp->compressed_ack_rcv_nxt != tp->rcv_nxt) {
