Re: [PATCH net] mac802154: wait for RCU readers when removing interfaces

[Kuniyuki Iwashima <kuniyu@google.com>]

From: Yousef Alhouseen <alhouseenyousef@gmail.com>
Date: Tue, 30 Jun 2026 23:18:08 +0200
> Queue wake, stop, and disable paths walk local->interfaces under RCU.
> The bulk hardware teardown path removes entries with list_del() and

The problematic part is list_del(), not unregister_netdevice().


> immediately unregisters their netdevices, so an asynchronous transmit

not immediately, unregister_netdevice() waits inflight RCU readers.
So, synchronize_rcu() should be unnecessary.

(Same remark for ieee802154_if_remove())

> completion can follow a poisoned list node in ieee802154_wake_queue().
> 
> Match ieee802154_if_remove(): use list_del_rcu() and wait for existing
> readers before unregistering each interface.
> 
> Fixes: 592dfbfc72f5 ("mac820154: move interface unregistration into iface")
> Reported-by: syzbot+36256deb69a588e9290e@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=36256deb69a588e9290e
> Cc: stable@vger.kernel.org
> Signed-off-by: Yousef Alhouseen <alhouseenyousef@gmail.com>
> ---
>  net/mac802154/iface.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/mac802154/iface.c b/net/mac802154/iface.c
> index 000be60d9580..73d82a015184 100644
> --- a/net/mac802154/iface.c
> +++ b/net/mac802154/iface.c
> @@ -703,7 +703,8 @@ void ieee802154_remove_interfaces(struct ieee802154_local *local)
>  
>  	mutex_lock(&local->iflist_mtx);
>  	list_for_each_entry_safe(sdata, tmp, &local->interfaces, list) {
> -		list_del(&sdata->list);
> +		list_del_rcu(&sdata->list);
> +		synchronize_rcu();
>  
>  		unregister_netdevice(sdata->dev);
>  	}
> --