[bug report] wifi: mt76: Check link_conf pointer in mt76_connac_mcu_sta_basic_tlv()

[Dan Carpenter]

Hello Shayne Chen,

This is a semi-automatic email about new static checker warnings.

Commit 9890624c1b39 ("wifi: mt76: Check link_conf pointer in
mt76_connac_mcu_sta_basic_tlv()") from Mar 11, 2025, leads to the
following Smatch complaint:

    drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c:394 mt76_connac_mcu_sta_basic_tlv()
    warn: variable dereferenced before check 'link_conf' (see line 376)

drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c
   375	{
   376		struct ieee80211_vif *vif = link_conf->vif;
                                            ^^^^^^^^^^^^^^
Dereferenced.

   377		struct sta_rec_basic *basic;
   378		struct tlv *tlv;
   379		int conn_type;
   380	
   381		tlv = mt76_connac_mcu_add_tlv(skb, STA_REC_BASIC, sizeof(*basic));
   382	
   383		basic = (struct sta_rec_basic *)tlv;
   384		basic->extra_info = cpu_to_le16(EXTRA_INFO_VER);
   385	
   386		if (newly && conn_state != CONN_STATE_DISCONNECT)
   387			basic->extra_info |= cpu_to_le16(EXTRA_INFO_NEW);
   388		basic->conn_state = conn_state;
   389	
   390		if (!link_sta) {
   391			basic->conn_type = cpu_to_le32(CONNECTION_INFRA_BC);
   392	
   393			if (vif->type == NL80211_IFTYPE_STATION &&
   394			    link_conf && !is_zero_ether_addr(link_conf->bssid)) {
                            ^^^^^^^^^
The patch adds a NULL dereference but it's too late.

   395				memcpy(basic->peer_addr, link_conf->bssid, ETH_ALEN);
   396				basic->aid = cpu_to_le16(vif->cfg.aid);

regards,
dan carpenter