mac80211: remove BUG_ON usage

These BUG_ON statements should never trigger, but in the unlikely
event that somebody does manage don't stop everything but simply
exit the code path with an error.

Leave the one BUG_ON where changing it would result in a NULL
pointer dereference.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/key.c

@@ -325,7 +325,8 @@ ieee80211_key_alloc(u32 cipher, int idx, size_t key_len,
 	struct ieee80211_key *key;
 	int i, j, err;
 
-	BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS);
+	if (WARN_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS))
+		return ERR_PTR(-EINVAL);
 
 	key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
 	if (!key)
@@ -481,8 +482,8 @@ int ieee80211_key_link(struct ieee80211_key *key,
 	int idx, ret;
 	bool pairwise;
 
-	BUG_ON(!sdata);
-	BUG_ON(!key);
+	if (WARN_ON(!sdata || !key))
+		return -EINVAL;
 
 	pairwise = key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE;
 	idx = key->conf.keyidx;

net/mac80211/mesh_pathtbl.c

@@ -287,8 +287,10 @@ static void mesh_path_move_to_queue(struct mesh_path *gate_mpath,
 	struct sk_buff_head failq;
 	unsigned long flags;
 
-	BUG_ON(gate_mpath == from_mpath);
-	BUG_ON(!gate_mpath->next_hop);
+	if (WARN_ON(gate_mpath == from_mpath))
+		return;
+	if (WARN_ON(!gate_mpath->next_hop))
+		return;
 
 	__skb_queue_head_init(&failq);
 

net/mac80211/mesh_sync.c

@@ -171,7 +171,7 @@ static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata,
 	u8 cap;
 
 	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
-	BUG_ON(!rcu_read_lock_held());
+	WARN_ON(!rcu_read_lock_held());
 	cap = beacon->meshconf->meshconf_cap;
 
 	spin_lock_bh(&ifmsh->sync_offset_lock);