linux-kernel - Re: [PATCH v3 2/9] misc: fastrpc: Fix DSP capabilities request

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Date: Thu, 30 May 2024 13:59:40 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Ekansh Gupta <quic_ekangupt@...cinc.com>
Cc: srinivas.kandagatla@...aro.org, linux-arm-msm@...r.kernel.org, 
	gregkh@...uxfoundation.org, quic_bkumar@...cinc.com, linux-kernel@...r.kernel.org, 
	quic_chennak@...cinc.com, stable <stable@...nel.org>
Subject: Re: [PATCH v3 2/9] misc: fastrpc: Fix DSP capabilities request

On Thu, May 30, 2024 at 03:50:20PM +0530, Ekansh Gupta wrote:
> Incorrect remote arguments are getting passed when requesting for
> capabilities from DSP.

Describe why and how they are incorrect.

> Also there is no requirement to update the
> PD type as it might cause problems for any PD other than user PD.

Also... means that these are two separate issues. There should be two
separate commits.

> In addition to this, the collected capability information is not
> getting copied properly to user. Add changes to address these
> problems and get correct DSP capabilities.
> 
> Fixes: 6c16fd8bdd40 ("misc: fastrpc: Add support to get DSP capabilities")
> Cc: stable <stable@...nel.org>
> Signed-off-by: Ekansh Gupta <quic_ekangupt@...cinc.com>
> ---
>  drivers/misc/fastrpc.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 4028cb96bcf2..61389795f498 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -1700,9 +1700,8 @@ static int fastrpc_get_info_from_dsp(struct fastrpc_user *fl, uint32_t *dsp_attr
>  	args[0].length = sizeof(dsp_attr_buf_len);
>  	args[0].fd = -1;
>  	args[1].ptr = (u64)(uintptr_t)&dsp_attr_buf[1];
> -	args[1].length = dsp_attr_buf_len;
> +	args[1].length = dsp_attr_buf_len * sizeof(uint32_t);

As you are skipping first entry, should there be (dsp_attr_buf_len - 1)
* sizeof(uint32_t).

>  	args[1].fd = -1;
> -	fl->pd = USER_PD;
>  
>  	return fastrpc_internal_invoke(fl, true, FASTRPC_DSP_UTILITIES_HANDLE,
>  				       FASTRPC_SCALARS(0, 1, 1), args);
> @@ -1730,7 +1729,7 @@ static int fastrpc_get_info_from_kernel(struct fastrpc_ioctl_capability *cap,
>  	if (!dsp_attributes)
>  		return -ENOMEM;
>  
> -	err = fastrpc_get_info_from_dsp(fl, dsp_attributes, FASTRPC_MAX_DSP_ATTRIBUTES_LEN);
> +	err = fastrpc_get_info_from_dsp(fl, dsp_attributes, FASTRPC_MAX_DSP_ATTRIBUTES);

So it looks like the argument was correct. It was passing length, not
the number of attributes. The only thing to fix is that args[1].length
should be dsp_attr_buf_len - sizeof(*dsp_attr_buf).

>  	if (err == DSP_UNSUPPORTED_API) {
>  		dev_info(&cctx->rpdev->dev,
>  			 "Warning: DSP capabilities not supported on domain: %d\n", domain);
> @@ -1783,7 +1782,7 @@ static int fastrpc_get_dsp_info(struct fastrpc_user *fl, char __user *argp)
>  	if (err)
>  		return err;
>  
> -	if (copy_to_user(argp, &cap.capability, sizeof(cap.capability)))
> +	if (copy_to_user(argp, &cap, sizeof(cap)))
>  		return -EFAULT;
>  
>  	return 0;
> -- 
> 2.43.0
> 

-- 
With best wishes
Dmitry