Re: [PATCH] i2c: rtl9300: Fix out-of-bounds bug in rtl9300_i2c_smbus_xfer

[Chris Packham]

Hi Alex,

On 16/06/2025 11:52, Alex Guo wrote:
> The data->block[0] variable comes from user. Without proper check,
> the variable may be very large to cause an out-of-bounds bug.
>
> Fix this bug by checking the value of data->block[0] first.
>
> Similar commit:
> 1. commit 39244cc7548 ("i2c: ismt: Fix an out-of-bounds bug in
> ismt_access()")
> 2. commit 92fbb6d1296 ("i2c: xgene-slimpro: Fix out-of-bounds
> bug in xgene_slimpro_i2c_xfer()")
>
> Signed-off-by: Alex Guo <alexguo1023@xxxxxxxxx>

Reviewed-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
Tested-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>

Thanks

> ---
>   drivers/i2c/busses/i2c-rtl9300.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-rtl9300.c b/drivers/i2c/busses/i2c-rtl9300.c
> index e064e8a4a1f0..568495720810 100644
> --- a/drivers/i2c/busses/i2c-rtl9300.c
> +++ b/drivers/i2c/busses/i2c-rtl9300.c
> @@ -281,6 +281,10 @@ static int rtl9300_i2c_smbus_xfer(struct i2c_adapter *adap, u16 addr, unsigned s
>   		ret = rtl9300_i2c_reg_addr_set(i2c, command, 1);
>   		if (ret)
>   			goto out_unlock;
> +		if (data->block[0] < 1 || data->block[0] > I2C_SMBUS_BLOCK_MAX) {
> +			ret = -EINVAL;
> +			goto out_unlock;
> +		}
>   		ret = rtl9300_i2c_config_xfer(i2c, chan, addr, data->block[0]);
>   		if (ret)
>   			goto out_unlock;