Hi Heiner,
On Sun, 07 Nov 2021 22:57:00 +0100, Heiner Kallweit wrote:
> If an invalid block size is provided, reject it instead of silently
> changing it to a supported value. Especially critical I see the case of
> a write transfer with block length 0. In this case we have no guarantee
> that the byte we would write is valid. When silently reducing a read to
> 32 bytes then we don't return an error and the caller may falsely
> assume that we returned the full requested data.
>
> If this change should break any (broken) caller, then I think we should
> fix the caller.
Fully agreed.
> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-i801.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
> index 2c48691d2..638198b4b 100644
> --- a/drivers/i2c/busses/i2c-i801.c
> +++ b/drivers/i2c/busses/i2c-i801.c
> @@ -761,6 +761,11 @@ static int i801_block_transaction(struct i801_priv *priv, union i2c_smbus_data *
> int result = 0;
> unsigned char hostc;
>
> + if (read_write == I2C_SMBUS_READ && command == I2C_SMBUS_BLOCK_DATA)
> + data->block[0] = I2C_SMBUS_BLOCK_MAX;
> + else if (data->block[0] < 1 || data->block[0] > I2C_SMBUS_BLOCK_MAX)
> + return -EPROTO;
> +
> if (command == I2C_SMBUS_I2C_BLOCK_DATA) {
> if (read_write == I2C_SMBUS_WRITE) {
> /* set I2C_EN bit in configuration register */
> @@ -774,16 +779,6 @@ static int i801_block_transaction(struct i801_priv *priv, union i2c_smbus_data *
> }
> }
>
> - if (read_write == I2C_SMBUS_WRITE
> - || command == I2C_SMBUS_I2C_BLOCK_DATA) {
> - if (data->block[0] < 1)
> - data->block[0] = 1;
> - if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
> - data->block[0] = I2C_SMBUS_BLOCK_MAX;
> - } else {
> - data->block[0] = 32; /* max for SMBus block reads */
> - }
> -
> /* Experience has shown that the block buffer can only be used for
> SMBus (not I2C) block transactions, even though the datasheet
> doesn't mention this limitation. */
Reviewed-by: Jean Delvare <jdelvare@xxxxxxx>
--
Jean Delvare
SUSE L3 Support
