Re: [PATCH 2/7] firmware: cs_dsp: Check for valid num_regs in cs_dsp_wseq_multi_write()

[Charles Keepax <ckeepax@opensource.cirrus.com>]

On Fri, Jan 31, 2025 at 01:56:33PM -0600, Fred Treven wrote:
> If a value of 0 or below is passed into cs_dsp_wseq_multi_write()
> the function will never enter its for loop.
> 
> Verify that num_regs passed into the function is valid
> and throw a user-visible error if not.
> 
> Signed-off-by: Fred Treven <ftreven@opensource.cirrus.com>
> ---
>  drivers/firmware/cirrus/cs_dsp.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/firmware/cirrus/cs_dsp.c b/drivers/firmware/cirrus/cs_dsp.c
> index 56315b0b5583..aacf6960d1ea 100644
> --- a/drivers/firmware/cirrus/cs_dsp.c
> +++ b/drivers/firmware/cirrus/cs_dsp.c
> @@ -3743,6 +3743,11 @@ int cs_dsp_wseq_multi_write(struct cs_dsp *dsp, struct cs_dsp_wseq *wseq,
>  {
>  	int i, ret;
>  
> +	if (num_regs <= 0) {
> +		cs_dsp_err(dsp, "Invalid number of regs: %d\n", num_regs);
> +		return -EINVAL;
> +	}
> +

This feels a little defensive, do we really need to check for
this? Normally num_regs is going to come from an ARRAY_SIZE or
something.

Thanks,
Charles