[PATCH v5] wifi: mt76: Fix NULL Dereference caused by mt76_connac_get_he_phy_cap()

[Matthias Brugger]

On 03/10/2024 20:09, Gax-c wrote:
> From: Zichen Xie <zichenxie0106 at gmail.com>
> 
> mt76_connac_get_he_phy_cap() may return a NULL pointer,
> leading to NULL Pointer Dereference.
> Add a NULL check for the returned pointer.
> 
> Fixes: a5c372f77aa7 ("wifi: mt76: mt7925: extend mt7925_mcu_bss_he_tlv for per-link BSS")
> Fixes: e6d557a78b60 ("mt76: mt7915: rely on mt76_connac_get_phy utilities")
> Fixes: 98686cd21624 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
> Signed-off-by: Zichen Xie <zichenxie0106 at gmail.com>
> ---
>   drivers/net/wireless/mediatek/mt76/mt7915/mcu.c | 5 +++++
>   drivers/net/wireless/mediatek/mt76/mt7925/mcu.c | 2 ++
>   drivers/net/wireless/mediatek/mt76/mt7996/mcu.c | 2 ++
>   3 files changed, 9 insertions(+)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
> index 87d0dd040001..762be3a37228 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
> @@ -551,6 +551,8 @@ mt7915_mcu_bss_he_tlv(struct sk_buff *skb, struct ieee80211_vif *vif,
>   	struct tlv *tlv;
>   
>   	cap = mt76_connac_get_he_phy_cap(phy->mt76, vif);
> +	if (!cap)
> +		return;
>   
>   	tlv = mt76_connac_mcu_add_tlv(skb, BSS_INFO_HE_BASIC, sizeof(*he));
>   
> @@ -1145,6 +1147,9 @@ mt7915_mcu_sta_bfer_he(struct ieee80211_sta *sta, struct ieee80211_vif *vif,
>   	u8 nss_mcs = mt7915_mcu_get_sta_nss(mcs_map);
>   	u8 snd_dim, sts;
>   
> +	if (!vc)
> +		return;
> +

That will already blow up at line:
         const struct ieee80211_he_cap_elem *ve = &vc->he_cap_elem;

This needs some more code changes.

Regards,
Matthias

>   	bf->tx_mode = MT_PHY_TYPE_HE_SU;
>   
>   	mt7915_mcu_sta_sounding_rate(bf);
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7925/mcu.c
> index 748ea6adbc6b..55e4cda2f20f 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7925/mcu.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7925/mcu.c
> @@ -2508,6 +2508,8 @@ mt7925_mcu_bss_he_tlv(struct sk_buff *skb, struct ieee80211_bss_conf *link_conf,
>   	struct tlv *tlv;
>   
>   	cap = mt76_connac_get_he_phy_cap(phy->mt76, link_conf->vif);
> +	if (!cap)
> +		return;
>   
>   	tlv = mt76_connac_mcu_add_tlv(skb, UNI_BSS_INFO_HE_BASIC, sizeof(*he));
>   
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
> index 6c445a9dbc03..55bb2d0e67e5 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
> @@ -798,6 +798,8 @@ mt7996_mcu_bss_he_tlv(struct sk_buff *skb, struct ieee80211_vif *vif,
>   	struct tlv *tlv;
>   
>   	cap = mt76_connac_get_he_phy_cap(phy->mt76, vif);
> +	if (!cap)
> +		return;
>   
>   	tlv = mt7996_mcu_add_uni_tlv(skb, UNI_BSS_INFO_HE_BASIC, sizeof(*he));
>