linux-kernel - [PATCH] mfd: mt6360: add bound check in regmap read/write function

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Message-Id: <1663143973-29254-1-git-send-email-u0084500@gmail.com>
Date:   Wed, 14 Sep 2022 16:26:13 +0800
From:   cy_huang <u0084500@...il.com>
To:     lee@...nel.org
Cc:     matthias.bgg@...il.com, gene_chen@...htek.com,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        ChiYuan Huang <cy_huang@...htek.com>, stable@...r.kernel.org
Subject: [PATCH] mfd: mt6360: add bound check in regmap read/write function

From: ChiYuan Huang <cy_huang@...htek.com>

Fix the potential risk for null pointer if bank index is over the maximimum.

Refer to the discussion list for the experiment result on mt6370.
https://lore.kernel.org/all/20220914013345.GA5802@cyhuang-hp-elitebook-840-g3.rt/
If not to check the bound, there is the same issue on mt6360.

Fixes: 3b0850440a06c (mfd: mt6360: Merge different sub-devices I2C read/write)
Cc: stable@...r.kernel.org
Signed-off-by: ChiYuan Huang <cy_huang@...htek.com>
---
 drivers/mfd/mt6360-core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/mfd/mt6360-core.c b/drivers/mfd/mt6360-core.c
index 6eaa677..d375333 100644
--- a/drivers/mfd/mt6360-core.c
+++ b/drivers/mfd/mt6360-core.c
@@ -410,6 +410,9 @@ static int mt6360_regmap_read(void *context, const void *reg, size_t reg_size,
 	u8 crc;
 	int ret;
 
+	if (bank >= MT6360_SLAVE_MAX)
+		return -EINVAL;
+
 	if (bank == MT6360_SLAVE_PMIC || bank == MT6360_SLAVE_LDO) {
 		crc_needed = true;
 		ret = mt6360_xlate_pmicldo_addr(&reg_addr, val_size);
@@ -460,6 +463,9 @@ static int mt6360_regmap_write(void *context, const void *val, size_t val_size)
 	int write_size = val_size - MT6360_REGMAP_REG_BYTE_SIZE;
 	int ret;
 
+	if (bank >= MT6360_SLAVE_MAX)
+		return -EINVAL;
+
 	if (bank == MT6360_SLAVE_PMIC || bank == MT6360_SLAVE_LDO) {
 		crc_needed = true;
 		ret = mt6360_xlate_pmicldo_addr(&reg_addr, val_size - MT6360_REGMAP_REG_BYTE_SIZE);
-- 
2.7.4