From 5f4f94e9f26cca6514474b307b59348b8485e711 Mon Sep 17 00:00:00 2001
From: ChiYuan Huang <cy_huang@richtek.com>
Date: Thu, 29 Sep 2022 10:00:17 +0800
Subject: [PATCH] mfd: mt6360: Add bounds checking in Regmap read/write call-backs
Git-commit: 5f4f94e9f26cca6514474b307b59348b8485e711
Patch-mainline: v6.2-rc1
References: git-fixes

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
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/mfd/mt6360-core.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/mt6360-core.c b/drivers/mfd/mt6360-core.c
index 6eaa6775b888..d3b32eb79837 100644
--- 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);
-- 
2.35.3