Re: [PATCH v3 6/6] bus: mhi: core: Add range checks for BHI and BHIe

[Hemant Kumar <hemantk@codeaurora.org>]

Hi Bhaumik,

On 5/5/21 10:08 AM, Bhaumik Bhatt wrote:
> When obtaining the BHI or BHIe offsets during the power up
> preparation phase, range checks are missing. These can help
> controller drivers avoid accessing any address outside of the
> MMIO region. Ensure that mhi_cntrl->reg_len is set before MHI
> registration as it is a required field and range checks will
> fail without it.
> 
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
> ---
>   drivers/bus/mhi/core/init.c | 15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index 1cc2f22..86ad06e 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -885,7 +885,8 @@ int mhi_register_controller(struct mhi_controller *mhi_cntrl,
>   	if (!mhi_cntrl || !mhi_cntrl->cntrl_dev || !mhi_cntrl->regs ||
>   	    !mhi_cntrl->runtime_get || !mhi_cntrl->runtime_put ||
>   	    !mhi_cntrl->status_cb || !mhi_cntrl->read_reg ||
> -	    !mhi_cntrl->write_reg || !mhi_cntrl->nr_irqs || !mhi_cntrl->irq)
> +	    !mhi_cntrl->write_reg || !mhi_cntrl->nr_irqs ||
> +	    !mhi_cntrl->irq || !mhi_cntrl->reg_len)
>   		return -EINVAL;
>   
>   	ret = parse_config(mhi_cntrl, config);
> @@ -1077,6 +1078,12 @@ int mhi_prepare_for_power_up(struct mhi_controller *mhi_cntrl)
>   		dev_err(dev, "Error getting BHI offset\n");
>   		goto error_reg_offset;
>   	}
> +
> +	if (bhi_off >= mhi_cntrl->reg_len) {
> +		dev_err(dev, "BHI offset is out of range\n");
Does is make sense to also log bhi_off and/or reg_len values in error if 
it helps in debugging
> +		ret = -EINVAL;
> +		goto error_reg_offset;
> +	}
>   	mhi_cntrl->bhi = mhi_cntrl->regs + bhi_off;
>   
>   	if (mhi_cntrl->fbc_download || mhi_cntrl->rddm_size) {
> @@ -1086,6 +1093,12 @@ int mhi_prepare_for_power_up(struct mhi_controller *mhi_cntrl)
>   			dev_err(dev, "Error getting BHIE offset\n");
>   			goto error_reg_offset;
>   		}
> +
> +		if (bhie_off >= mhi_cntrl->reg_len) {
> +			dev_err(dev, "BHIe offset is out of range\n");
Same comment as above
> +			ret = -EINVAL;
> +			goto error_reg_offset;
> +		}
>   		mhi_cntrl->bhie = mhi_cntrl->regs + bhie_off;
>   	}
>   
> 

Thanks,
Hemant
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