This is a note to let you know that I've just added the patch titled net: Fix a data-race around sysctl_tstamp_allow_data. to the 4.19-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: net-fix-a-data-race-around-sysctl_tstamp_allow_data.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 9ec3dc9f2520b4e019f822b503aae7461cb294d8 Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> Date: Tue Aug 23 10:46:50 2022 -0700 net: Fix a data-race around sysctl_tstamp_allow_data. [ Upstream commit d2154b0afa73c0159b2856f875c6b4fe7cf6a95e ] While reading sysctl_tstamp_allow_data, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: b245be1f4db1 ("net-timestamp: no-payload only sysctl") Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/core/skbuff.c b/net/core/skbuff.c index c623c129d0ab6..e0be1f8651bbe 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4377,7 +4377,7 @@ static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly) { bool ret; - if (likely(sysctl_tstamp_allow_data || tsonly)) + if (likely(READ_ONCE(sysctl_tstamp_allow_data) || tsonly)) return true; read_lock_bh(&sk->sk_callback_lock);