wifi: libertas_tf: fix use-after-free in lbtf_free_adapter()

wifi: libertas_tf: fix use-after-free in lbtf_free_adapter()

lbtf_free_adapter() calls timer_delete(&priv->command_timer), which does
not wait for a running command_timer_fn() callback. lbtf_free_adapter()
runs on the teardown path right before ieee80211_free_hw() frees priv,
both in lbtf_remove_card() and in the probe error path. command_timer is
armed by mod_timer() in lbtf_cmd() whenever a firmware command is sent.
command_timer_fn() dereferences priv. If a command times out as the
device is removed, command_timer_fn() runs concurrently with teardown and
dereferences priv after it has been freed.

This is the same use-after-free that commit 03cc8f90d053 ("wifi: libertas:
fix use-after-free in lbs_free_adapter()") fixed in the sibling libertas
driver. The libertas_tf variant has the identical pattern and was left
unchanged. Use timer_delete_sync() so any in-flight callback completes
before priv is freed.

Fixes: 06b16ae53192 ("libertas_tf: main.c, data paths and mac80211 handlers")
Cc: stable@vger.kernel.org
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Link: https://patch.msgid.link/178211481807.2212567.8773346114561900100@maoyixie.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>