mfd: mt6360: Add bounds checking in Regmap read/write call-backs

ChiYuan Huang · lag-linaro · commit 5f4f94e9f26c · 2022-12-07T13:28:08.000Z
Fix the potential risk of OOB read if bank index is over the maximum. 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. Cc: stable@vger.kernel.org Fixes: 3b08504 (mfd: mt6360: Merge different sub-devices I2C read/write) Signed-off-by: ChiYuan Huang <cy_huang@richtek.com> Signed-off-by: Lee Jones <lee@kernel.org> Link: https://lore.kernel.org/r/1664416817-31590-1-git-send-email-u0084500@gmail.com
diff --git a/drivers/mfd/mt6360-core.c b/drivers/mfd/mt6360-core.c
@@ -402,14 +402,19 @@ static int mt6360_regmap_read(void *context, const void *reg, size_t reg_size,
 	struct mt6360_ddata *ddata = context;
 	u8 bank = *(u8 *)reg;
 	u8 reg_addr = *(u8 *)(reg + 1);
-	struct i2c_client *i2c = ddata->i2c[bank];
+	struct i2c_client *i2c;
 	bool crc_needed = false;
 	u8 *buf;
 	int buf_len = MT6360_ALLOC_READ_SIZE(val_size);
 	int read_size = val_size;
 	u8 crc;
 	int ret;
 
+	if (bank >= MT6360_SLAVE_MAX)
+		return -EINVAL;
+
+	i2c = ddata->i2c[bank];
+
 	if (bank == MT6360_SLAVE_PMIC || bank == MT6360_SLAVE_LDO) {
 		crc_needed = true;
 		ret = mt6360_xlate_pmicldo_addr(&reg_addr, val_size);
@@ -453,13 +458,18 @@ static int mt6360_regmap_write(void *context, const void *val, size_t val_size)
 	struct mt6360_ddata *ddata = context;
 	u8 bank = *(u8 *)val;
 	u8 reg_addr = *(u8 *)(val + 1);
-	struct i2c_client *i2c = ddata->i2c[bank];
+	struct i2c_client *i2c;
 	bool crc_needed = false;
 	u8 *buf;
 	int buf_len = MT6360_ALLOC_WRITE_SIZE(val_size);
 	int write_size = val_size - MT6360_REGMAP_REG_BYTE_SIZE;
 	int ret;
 
+	if (bank >= MT6360_SLAVE_MAX)
+		return -EINVAL;
+
+	i2c = ddata->i2c[bank];
+
 	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);
