Re: [PATCH] mac802154: add a check for slave data list before delete

On Thu, 14 Nov 2024 09:00:25 +0800, Lizhi Xu wrote:

On Wed, 13 Nov 2024 13:29:55 +0300, Dmitry Antipov wrote:

quoted

On 11/12/24 4:41 PM, Lizhi Xu wrote:

quoted

  	mutex_lock(&sdata->local->iflist_mtx);
+	if (list_empty(&sdata->local->interfaces)) {
+		mutex_unlock(&sdata->local->iflist_mtx);
+		return;
+	}
  	list_del_rcu(&sdata->list);
  	mutex_unlock(&sdata->local->iflist_mtx);

Note https://syzkaller.appspot.com/text?tag=ReproC&x=12a9f740580000 makes an
attempt to connect the only device. How this is expected to work if there are
more than one device?

There are two locks (rtnl and iflist_mtx) to protection and synchronization
local->interfaces, so no need to worry about multiple devices.

In other words, this case is a race between removing the 802154 master
and the user sendmsg actively deleting the slave.
Then when the master is removed, there is no need to execute the latter to
remove the slave, because all the slave devices have been deleted when the
master device is removed..

Lizhi