[PATCH 06/10] wifi: mt76: mt7915: validate free-block response length

[Jiale Yao <yaojiale02@163.com>]

The free-block query reads the first response byte without checking that
the firmware returned any payload. A zero-length response can therefore
cause an out-of-bounds read.

Require the block-count byte before accessing it.

Fixes: bbc1d4154ec1 ("mt76: mt7915: add default calibrated data support")
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 drivers/net/wireless/mediatek/mt76/mt7915/mcu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
index 7009a3a3edd2..05614b99165b 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
@@ -2985,6 +2985,10 @@ int mt7915_mcu_get_eeprom_free_block(struct mt7915_dev *dev, u8 *block_num)
 					&req, sizeof(req), true, &skb);
 	if (ret)
 		return ret;
+	if (skb->len < sizeof(*block_num)) {
+		dev_kfree_skb(skb);
+		return -EINVAL;
+	}
 
 	*block_num = *(u8 *)skb->data;
 	dev_kfree_skb(skb);
-- 
2.34.1