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Commit dfdc635d authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Greg Kroah-Hartman
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tcp: Fix a data-race around sysctl_tcp_limit_output_bytes. 



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: 46d3ceab ("tcp: TCP Small Queues")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d62e255e

net/ipv4/tcp_output.c

+1 −1
Original line number Diff line number Diff line
@@ -2276,7 +2276,7 @@ static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, 
		      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) &&