Re: [PATCH v2 1/2] remoteproc: qcom_q6v5_mss: Add modem debug policy support

[Bjorn Andersson]

On Tue 21 Jul 04:29 PDT 2020, Sibi Sankar wrote:

> Add modem debug policy support which will enable coredumps and live
> debug support when the msadp firmware is present on secure devices.
> 
> Signed-off-by: Sibi Sankar <sibis@xxxxxxxxxxxxxx>
> ---
> 
> v2:
>  * Use request_firmware_direct [Bjorn]
>  * Use Bjorn's template to show if debug policy is present
>  * Add size check to prevent memcpy out of bounds [Bjorn]
> 
>  drivers/remoteproc/qcom_q6v5_mss.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
> index 0b6f260eb5349..49cd16e050533 100644
> --- a/drivers/remoteproc/qcom_q6v5_mss.c
> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
> @@ -189,6 +189,7 @@ struct q6v5 {
>  	phys_addr_t mba_phys;
>  	void *mba_region;
>  	size_t mba_size;
> +	size_t dp_size;
>  
>  	phys_addr_t mpss_phys;
>  	phys_addr_t mpss_reloc;
> @@ -408,6 +409,14 @@ static int q6v5_xfer_mem_ownership(struct q6v5 *qproc, int *current_perm,
>  static int q6v5_load(struct rproc *rproc, const struct firmware *fw)
>  {
>  	struct q6v5 *qproc = rproc->priv;
> +	const struct firmware *dp_fw;
> +
> +	if (!request_firmware_direct(&dp_fw, "msadp", qproc->dev) && fw->size <= SZ_1M &&
> +	    (SZ_1M + dp_fw->size) <= qproc->mba_size) {
> +		memcpy(qproc->mba_region + SZ_1M, dp_fw->data, dp_fw->size);
> +		qproc->dp_size = dp_fw->size;
> +		release_firmware(dp_fw);

If request_firmware_direct() succeeds, but return a firmware blob bigger
than mba_size - SZ_1M you won't get here and will end up leaking dp_fw.

Additionally, there really isn't a need for requesting the firmware in
the first place if fw->size > SZ_1M.

So I think it's better if you break this out in it's own function where
you don't need to squeeze everything into one or two conditionals.

Regards,
Bjorn

> +	}
>  
>  	memcpy(qproc->mba_region, fw->data, fw->size);
>  
> @@ -896,6 +905,10 @@ static int q6v5_mba_load(struct q6v5 *qproc)
>  	}
>  
>  	writel(qproc->mba_phys, qproc->rmb_base + RMB_MBA_IMAGE_REG);
> +	if (qproc->dp_size) {
> +		writel(qproc->mba_phys + SZ_1M, qproc->rmb_base + RMB_PMI_CODE_START_REG);
> +		writel(qproc->dp_size, qproc->rmb_base + RMB_PMI_CODE_LENGTH_REG);
> +	}
>  
>  	ret = q6v5proc_reset(qproc);
>  	if (ret)
> @@ -1257,7 +1270,8 @@ static int q6v5_start(struct rproc *rproc)
>  	if (ret)
>  		return ret;
>  
> -	dev_info(qproc->dev, "MBA booted, loading mpss\n");
> +	dev_info(qproc->dev, "MBA booted with%s debug policy, loading mpss\n",
> +		 qproc->dp_size ? "" : "out");
>  
>  	ret = q6v5_mpss_load(qproc);
>  	if (ret)
> -- 
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> a Linux Foundation Collaborative Project
>