[PATCH 5.15.y 2/2] wifi: mt76: mt7915: bound the device EEPROM address before the EFUSE copy

[Sasha Levin <sashal@kernel.org>]

From: Bryam Vargas <hexlabsecurity@proton.me>

[ Upstream commit 44b5adfe49499f53002737f5fe81d608c08122fc ]

mt7915_mcu_get_eeprom() copies a fixed EFUSE block into the driver's
dev->mt76.eeprom.data buffer at the offset reported by the MCU response
(res->addr, a device-controlled __le32) without checking it against the
buffer size. A malicious or malfunctioning device can report an arbitrary
address and drive a 16-byte out-of-bounds write past eeprom.data.

Reject a response whose address would place the copy outside eeprom.data
before deriving the destination pointer. Devices that echo the requested
in-bounds offset are unaffected.

Fixes: e57b7901469f ("mt76: add mac80211 driver for MT7915 PCIe-based chipsets")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Link: https://patch.msgid.link/20260625-b4-disp-16f99062-v1-1-aee52ecf61b9@proton.me
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt7915/mcu.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
index 7c60112a35d15..180a80616caca 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
@@ -3467,8 +3467,15 @@ int mt7915_mcu_get_eeprom(struct mt7915_dev *dev, u32 offset, u8 *read_buf)
 		return ret;
 
 	res = (struct mt7915_mcu_eeprom_info *)skb->data;
-	if (!buf)
-		buf = dev->mt76.eeprom.data + le32_to_cpu(res->addr);
+	if (!buf) {
+		u32 addr = le32_to_cpu(res->addr);
+
+		if (addr > dev->mt76.eeprom.size - MT7915_EEPROM_BLOCK_SIZE) {
+			dev_kfree_skb(skb);
+			return -EINVAL;
+		}
+		buf = dev->mt76.eeprom.data + addr;
+	}
 	memcpy(buf, res->data, MT7915_EEPROM_BLOCK_SIZE);
 
 	dev_kfree_skb(skb);
-- 
2.53.0