[PATCH] mfd: mt6370: add bounds checking to regmap_read/write functions

[Dan Carpenter]

It looks like there are a potential out of bounds accesses in the
read/write() functions.  Also can "len" be negative?  Let's check for
that too.

Fixes: ab9905c5e38e ("mfd: mt6370: Add MediaTek MT6370 support")
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
---
>From static analysis.  This code is obviously harmless however it may
not be required.  The regmap range checking is slightly complicated and
I haven't remembered where all it's done.

 drivers/mfd/mt6370.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/mfd/mt6370.c b/drivers/mfd/mt6370.c
index cf19cce2fdc0..fd5e1d6a0272 100644
--- a/drivers/mfd/mt6370.c
+++ b/drivers/mfd/mt6370.c
@@ -190,6 +190,9 @@ static int mt6370_regmap_read(void *context, const void *reg_buf,
 	bank_idx = u8_buf[0];
 	bank_addr = u8_buf[1];
 
+	if (bank_idx >= ARRAY_SIZE(info->i2c))
+		return -EINVAL;
+
 	ret = i2c_smbus_read_i2c_block_data(info->i2c[bank_idx], bank_addr,
 					    val_size, val_buf);
 	if (ret < 0)
@@ -211,6 +214,9 @@ static int mt6370_regmap_write(void *context, const void *data, size_t count)
 	bank_idx = u8_buf[0];
 	bank_addr = u8_buf[1];
 
+	if (len < 0 || bank_idx >= ARRAY_SIZE(info->i2c))
+		return -EINVAL;
+
 	return i2c_smbus_write_i2c_block_data(info->i2c[bank_idx], bank_addr,
 					      len, data + MT6370_MAX_ADDRLEN);
 }
-- 
2.35.1