This is a note to let you know that I've just added the patch titled tcp: annotate data-race around challenge_timestamp to the 5.19-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-annotate-data-race-around-challenge_timestamp.patch and it can be found in the queue-5.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 837f367e4465cbe98c61781c1a6d31f26ef4b3a1 Author: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Tue Aug 30 11:56:55 2022 -0700 tcp: annotate data-race around challenge_timestamp [ Upstream commit 8c70521238b7863c2af607e20bcba20f974c969b ] challenge_timestamp can be read an written by concurrent threads. This was expected, but we need to annotate the race to avoid potential issues. Following patch moves challenge_timestamp and challenge_count to per-netns storage to provide better isolation. Fixes: 354e4aa391ed ("tcp: RFC 5961 5.2 Blind Data Injection Attack Mitigation") Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Acked-by: Neal Cardwell <ncardwell@xxxxxxxxxx> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index b1637990d5708..e5435156e545d 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3630,11 +3630,11 @@ static void tcp_send_challenge_ack(struct sock *sk) /* Then check host-wide RFC 5961 rate limit. */ now = jiffies / HZ; - if (now != challenge_timestamp) { + if (now != READ_ONCE(challenge_timestamp)) { u32 ack_limit = READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit); u32 half = (ack_limit + 1) >> 1; - challenge_timestamp = now; + WRITE_ONCE(challenge_timestamp, now); WRITE_ONCE(challenge_count, half + prandom_u32_max(ack_limit)); } count = READ_ONCE(challenge_count);