mac80211: fix memory leak

BugLink: https://bugs.launchpad.net/bugs/1883917

commit ea32f065 upstream.

On error we jumped to the error label and returned the error code but we
missed releasing sinfo.

Fixes: 5fe74014172d ("mac80211: avoid excessive stack usage in sta_info")
Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

net/mac80211/sta_info.c

@@ -555,6 +555,7 @@ static int sta_info_insert_finish(struct sta_info *sta) __acquires(RCU)
 	__cleanup_single_sta(sta);
  out_err:
 	mutex_unlock(&local->sta_mtx);
+	kfree(sinfo);
 	rcu_read_lock();
 	return err;
 }