[PATCH 5.15 47/69] tcp: Fix data-races around sk_pacing_rate.

Greg Kroah-Hartman
2022-08-01T12:08:42Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 59bf6c65a09fff74215517aecffbbdcd67df76e3 ]

While reading sysctl_tcp_pacing_(ss|ca)_ratio, they can be changed
concurrently. Thus, we need to add READ_ONCE() to their readers.

Fixes: 43e122b014c9 ("tcp: refine pacing rate determination")
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>
---
net/ipv4/tcp_input.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 018be3f346e6..566745f527fe 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -902,9 +902,9 @@ static void tcp_update_pacing_rate(struct sock *sk)
* end of slow start and should slow down.
*/
if (tcp_snd_cwnd(tp) < tp->snd_ssthresh / 2)
- rate *= sock_net(sk)->ipv4.sysctl_tcp_pacing_ss_ratio;
+ rate *= READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_pacing_ss_ratio);
else
- rate *= sock_net(sk)->ipv4.sysctl_tcp_pacing_ca_ratio;
+ rate *= READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_pacing_ca_ratio);

rate *= max(tcp_snd_cwnd(tp), tp->packets_out);

--
2.35.1