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_delay_ns.
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_dela.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 c49e789b7d79b86dd80db24d79c0ba77a513ead5
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Fri Jul 22 11:22:01 2022 -0700
tcp: Fix a data-race around sysctl_tcp_comp_sack_delay_ns.
[ Upstream commit 4866b2b0f7672b6d760c4b8ece6fb56f965dcc8a ]
While reading sysctl_tcp_comp_sack_delay_ns, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its reader.
Fixes: 6d82aa242092 ("tcp: add tcp_comp_sack_delay_ns 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 38412d93400a..b71866aba426 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5262,7 +5262,8 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible)
if (tp->srtt_us && tp->srtt_us < rtt)
rtt = tp->srtt_us;
- delay = min_t(unsigned long, sock_net(sk)->ipv4.sysctl_tcp_comp_sack_delay_ns,
+ delay = min_t(unsigned long,
+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_comp_sack_delay_ns),
rtt * (NSEC_PER_USEC >> 3)/20);
sock_hold(sk);
hrtimer_start(&tp->compressed_ack_timer, ns_to_ktime(delay),
