[PATCH 6.12.y] wifi: mt76: mt7996: bound the device EEPROM address before the EFUSE copy

[Sasha Levin <sashal@kernel.org>]

From: Bryam Vargas <hexlabsecurity@proton.me>

[ Upstream commit 13b3c29a782033ce4a230be9e5618032813dbcd4 ]

mt7996_mcu_get_eeprom() derives the destination of the EFUSE/EXT block
copy from the address reported by the MCU response (event->addr, a
device-controlled __le32) and clamps only the copy length, never the
destination offset into dev->mt76.eeprom.data. A malicious or
malfunctioning device can report an arbitrary address and drive an
out-of-bounds write of up to MT7996_EXT_EEPROM_BLOCK_SIZE bytes 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: 98686cd21624 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Link: https://patch.msgid.link/20260625-b4-disp-16f99062-v1-2-aee52ecf61b9@proton.me
Signed-off-by: Felix Fietkau <nbd@nbd.name>
[ adapted mt7996_mcu_get_eeprom() changes to the older fixed 16-byte EFUSE implementation. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt7996/mcu.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
index a5693efee74b8..ab54443b1102c 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
@@ -3586,7 +3586,13 @@ int mt7996_mcu_get_eeprom(struct mt7996_dev *dev, u32 offset)
 	valid = le32_to_cpu(*(__le32 *)(skb->data + 16));
 	if (valid) {
 		u32 addr = le32_to_cpu(*(__le32 *)(skb->data + 12));
-		u8 *buf = (u8 *)dev->mt76.eeprom.data + addr;
+		u8 *buf;
+
+		if (addr > dev->mt76.eeprom.size - MT7996_EEPROM_BLOCK_SIZE) {
+			dev_kfree_skb(skb);
+			return -EINVAL;
+		}
+		buf = (u8 *)dev->mt76.eeprom.data + addr;
 
 		skb_pull(skb, 48);
 		memcpy(buf, skb->data, MT7996_EEPROM_BLOCK_SIZE);
-- 
2.53.0