This is a note to let you know that I've just added the patch titled net/sched: taprio: Check if socket flags are valid to the 5.4-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-sched-taprio-check-if-socket-flags-are-valid.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f82b03d432ddaf27a9c6ee708e99fcccbd6f3ab9 Author: Benedikt Spranger <b.spranger@xxxxxxxxxxxxx> Date: Fri Apr 8 11:47:45 2022 +0200 net/sched: taprio: Check if socket flags are valid [ Upstream commit e8a64bbaaad1f6548cec5508297bc6d45e8ab69e ] A user may set the SO_TXTIME socket option to ensure a packet is send at a given time. The taprio scheduler has to confirm, that it is allowed to send a packet at that given time, by a check against the packet time schedule. The scheduler drop the packet, if the gates are closed at the given send time. The check, if SO_TXTIME is set, may fail since sk_flags are part of an union and the union is used otherwise. This happen, if a socket is not a full socket, like a request socket for example. Add a check to verify, if the union is used for sk_flags. Fixes: 4cfd5779bd6e ("taprio: Add support for txtime-assist mode") Signed-off-by: Benedikt Spranger <b.spranger@xxxxxxxxxxxxx> Reviewed-by: Kurt Kanzenbach <kurt@xxxxxxxxxxxxx> Acked-by: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index b268e6130451..4c26f7fb32b3 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -427,7 +427,8 @@ static int taprio_enqueue(struct sk_buff *skb, struct Qdisc *sch, if (unlikely(!child)) return qdisc_drop(skb, sch, to_free); - if (skb->sk && sock_flag(skb->sk, SOCK_TXTIME)) { + /* sk_flags are only safe to use on full sockets. */ + if (skb->sk && sk_fullsock(skb->sk) && sock_flag(skb->sk, SOCK_TXTIME)) { if (!is_valid_interval(skb, sch)) return qdisc_drop(skb, sch, to_free); } else if (TXTIME_ASSIST_IS_ENABLED(q->flags)) {