[PATCH 1/3] wifi: mt76: mt7921: validate NIC capability payload lengths

[Jiale Yao]

The NIC capability parser checks that each declared payload fits in the
skb, but it does not ensure that the payload is large enough for the
selected capability. A truncated firmware response can therefore make
the driver read beyond the current TLV while copying fixed-size fields or
parsing capability structures.

Validate every consumed payload before accessing it and reject the
response when a known capability is shorter than its fixed data.

Fixes: dab35009fc1c ("wifi: mt76: mt7921: move connac nic capability handling to mt7921")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jiale Yao <yaojiale02@xxxxxxx>
---
 .../net/wireless/mediatek/mt76/mt7921/mcu.c   | 41 +++++++++++++++----
 1 file changed, 33 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
index 25638c68c468..c960648b2b61 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
@@ -521,8 +521,8 @@ static int mt7921_load_clc(struct mt792x_dev *dev, const char *fw_name)
 	return ret;
 }
 
-static void mt7921_mcu_parse_tx_resource(struct mt76_dev *dev,
-					 struct sk_buff *skb)
+static bool mt7921_mcu_parse_tx_resource(struct mt76_dev *dev,
+					 struct sk_buff *skb, int len)
 {
 	struct mt76_sdio *sdio = &dev->sdio;
 	struct mt7921_tx_resource {
@@ -537,6 +537,9 @@ static void mt7921_mcu_parse_tx_resource(struct mt76_dev *dev,
 		u8 pad[3];
 	} __packed * tx_res;
 
+	if (len < sizeof(*tx_res))
+		return false;
+
 	tx_res = (struct mt7921_tx_resource *)skb->data;
 	sdio->sched.pse_data_quota = le32_to_cpu(tx_res->pse_data_quota);
 	sdio->pse_mcu_quota_max = le32_to_cpu(tx_res->pse_mcu_quota);
@@ -546,10 +549,12 @@ static void mt7921_mcu_parse_tx_resource(struct mt76_dev *dev,
 	sdio->sched.ple_data_quota = le32_to_cpu(tx_res->ple_data_quota);
 	sdio->sched.pse_page_size = le16_to_cpu(tx_res->pse_page_size);
 	sdio->sched.deficit = tx_res->pp_padding;
+
+	return true;
 }
 
-static void mt7921_mcu_parse_phy_cap(struct mt76_dev *dev,
-				     struct sk_buff *skb)
+static bool mt7921_mcu_parse_phy_cap(struct mt76_dev *dev,
+				     struct sk_buff *skb, int len)
 {
 	struct mt7921_phy_cap {
 		u8 ht;
@@ -571,12 +576,17 @@ static void mt7921_mcu_parse_phy_cap(struct mt76_dev *dev,
 		WF0_5G
 	};
 
+	if (len < sizeof(*cap))
+		return false;
+
 	cap = (struct mt7921_phy_cap *)skb->data;
 
 	dev->phy.antenna_mask = BIT(cap->nss) - 1;
 	dev->phy.chainmask = dev->phy.antenna_mask;
 	dev->phy.cap.has_2ghz = cap->hw_path & BIT(WF0_24G);
 	dev->phy.cap.has_5ghz = cap->hw_path & BIT(WF0_5G);
+
+	return true;
 }
 
 static int mt7921_mcu_get_nic_capability(struct mt792x_phy *mphy)
@@ -620,20 +630,30 @@ static int mt7921_mcu_get_nic_capability(struct mt792x_phy *mphy)
 
 		switch (le32_to_cpu(tlv->type)) {
 		case MT_NIC_CAP_6G:
+			if (len < sizeof(skb->data[0]))
+				goto invalid;
+
 			phy->cap.has_6ghz = skb->data[0];
 			break;
 		case MT_NIC_CAP_MAC_ADDR:
+			if (len < ETH_ALEN)
+				goto invalid;
+
 			memcpy(phy->macaddr, (void *)skb->data, ETH_ALEN);
 			break;
 		case MT_NIC_CAP_PHY:
-			mt7921_mcu_parse_phy_cap(phy->dev, skb);
+			if (!mt7921_mcu_parse_phy_cap(phy->dev, skb, len))
+				goto invalid;
 			break;
 		case MT_NIC_CAP_TX_RESOURCE:
-			if (mt76_is_sdio(phy->dev))
-				mt7921_mcu_parse_tx_resource(phy->dev,
-							     skb);
+			if (mt76_is_sdio(phy->dev) &&
+			    !mt7921_mcu_parse_tx_resource(phy->dev, skb, len))
+				goto invalid;
 			break;
 		case MT_NIC_CAP_CHIP_CAP:
+			if (len < sizeof(mphy->chip_cap))
+				goto invalid;
+
 			memcpy(&mphy->chip_cap, (void *)skb->data, sizeof(u64));
 			break;
 		default:
@@ -641,6 +661,11 @@ static int mt7921_mcu_get_nic_capability(struct mt792x_phy *mphy)
 		}
 		skb_pull(skb, len);
 	}
+
+	goto out;
+
+invalid:
+	ret = -EINVAL;
 out:
 	dev_kfree_skb(skb);
 
-- 
2.34.1