From: Kuniyuki Iwashima kuniyu@amazon.com
commit db3815a2fa691da145cfbe834584f31ad75df9ff upstream.
While reading sysctl_tcp_challenge_ack_limit, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader.
Fixes: 282f23c6ee34 ("tcp: implement RFC 5961 3.2") 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_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3629,7 +3629,7 @@ static void tcp_send_challenge_ack(struc /* Then check host-wide RFC 5961 rate limit. */ now = jiffies / HZ; if (now != challenge_timestamp) { - u32 ack_limit = net->ipv4.sysctl_tcp_challenge_ack_limit; + u32 ack_limit = READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit); u32 half = (ack_limit + 1) >> 1;
challenge_timestamp = now;