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

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Message-ID: <32750882-2e4c-44b7-af6d-a1ec0857b69a@linaro.org>
Date: Fri, 31 May 2024 10:33:29 +0100
From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To: Ekansh Gupta <quic_ekangupt@...cinc.com>, linux-arm-msm@...r.kernel.org
Cc: 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 30/05/2024 11:20, Ekansh Gupta wrote:
> Incorrect remote arguments are getting passed when requesting for
> capabilities from DSP. Also there is no requirement to update the
> PD type as it might cause problems for any PD other than user PD.
> 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);
This does not look correct,

we have allocated buffer of size FASTRPC_MAX_DSP_ATTRIBUTES_LEN which is
already (sizeof(u32) * FASTRPC_MAX_DSP_ATTRIBUTES)

now this patch multiplies with again sizeof(uint32_t), this is going to 
send dsp incorrect size for buffer and overrun the buffer size.



>   	args[1].fd = -1;
> -	fl->pd = USER_PD;
another patch may be.

>   
>   	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);

You change this again to send FASTRPC_MAX_DSP_ATTRIBUTES instead of 
FASTRPC_MAX_DSP_ATTRIBUTES_LEN but why?


>   	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)))

Why are we copying the full struct here? All that user needs is 
cap.capability?



--srini


>   		return -EFAULT;
>   
>   	return 0;