[PATCH 5.10 19/65] tcp: Fix a data-race around sysctl_tcp_limit_output_bytes.

Greg Kroah-Hartman
2022-08-01T11:53:27Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

commit 9fb90193fbd66b4c5409ef729fd081861f8b6351 upstream.

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

Fixes: 46d3ceabd8d9 ("tcp: TCP Small Queues")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/tcp_output.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2499,7 +2499,7 @@ static bool tcp_small_queue_check(struct
sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift));
if (sk->sk_pacing_status == SK_PACING_NONE)
limit = min_t(unsigned long, limit,
- sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes);
+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes));
limit <<= factor;

if (static_branch_unlikely(&tcp_tx_delay_enabled) &&