If we fail to add an interface in mwifiex_add_virtual_intf(), we might
hit a BUG_ON() in the networking code, because we didn't tear things
down properly. Among the problems:
(a) when failing to allocate workqueues, we fail to unregister the
netdev before calling free_netdev()
(b) even if we do try to unregister the netdev, we're still holding the
rtnl lock, so the device never properly unregistered; we'll be at
state NETREG_UNREGISTERING, and then hit free_netdev()'s:
BUG_ON(dev->reg_state != NETREG_UNREGISTERED);
(c) we're allocating some dependent resources (e.g., DFS workqueues)
after we've registered the interface; this may or may not cause
problems, but it's good practice to allocate these before registering
(d) we're not even trying to unwind anything when mwifiex_send_cmd() or
mwifiex_sta_init_cmd() fail
To fix these issues, let's:
* add a stacked set of error handling labels, to keep error handling
consistent and properly ordered (resolving (a) and (d))
* move the workqueue allocations before the registration (to resolve
(c); also resolves (b) by avoiding error cases where we have to
unregister)
[Incidentally, it's pretty easy to interrupt the alloc_workqueue() in,
e.g., the following:
iw phy phy0 interface add mlan0 type station
by sending it SIGTERM.]
This bugfix covers commits like commit 7d652034d1 ("mwifiex: channel
switch support for mwifiex"), but parts of this bug exist all the way
back to the introduction of dynamic interface handling in commit
93a1df48d2 ("mwifiex: add cfg80211 handlers add/del_virtual_intf").
Cc: <stable@vger.kernel.org>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
8535107aa4