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

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: 3b0850440a06c (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
index 6eaa6775b888583ed3a97d1f290cae6de71028b1..d3b32eb79837755a7d31cfd73b3d813e44f40fd2 100644 (file)
--- a/drivers/mfd/mt6360-core.c
+++ b/drivers/mfd/mt6360-core.c
@@ -402,7 +402,7 @@ 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);
@@ -410,6 +410,11 @@ 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;
+
+       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);