From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org
Cc: Bryam Vargas <hexlabsecurity@proton.me>,
	Felix Fietkau <nbd@nbd.name>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.18.y 1/2] wifi: mt76: mt7996: bound the device EEPROM address before the EFUSE copy
Date: Wed,  9 Sep 2026 21:17:27 -0400
Message-ID: <20260910011728.3833391-1-sashal@kernel.org>
In-Reply-To: <2026090414-routine-poster-2605@gregkh>
References: <2026090414-routine-poster-2605@gregkh>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

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>
[ Replaced the mode-dependent block size with MT7996_EEPROM_BLOCK_SIZE for the older EFUSE-only 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 72851399575f9..ee9716868c907 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
@@ -3866,8 +3866,14 @@ int mt7996_mcu_get_eeprom(struct mt7996_dev *dev, u32 offset, u8 *buf, u32 buf_l
 	if (valid) {
 		u32 addr = le32_to_cpu(*(__le32 *)(skb->data + 12));
 
-		if (!buf)
+		if (!buf) {
+			if (addr > dev->mt76.eeprom.size -
+			    MT7996_EEPROM_BLOCK_SIZE) {
+				dev_kfree_skb(skb);
+				return -EINVAL;
+			}
 			buf = (u8 *)dev->mt76.eeprom.data + addr;
+		}
 		if (!buf_len || buf_len > MT7996_EEPROM_BLOCK_SIZE)
 			buf_len = MT7996_EEPROM_BLOCK_SIZE;
 
-- 
2.53.0