Re: [PATCH v1 0/3] ASoC: Add bounds checking for written values

From: Mark Brown <broonie@kernel.org>
To: Jaroslav Kysela <perex@perex.cz>
Cc: alsa-devel@alsa-project.org, Liam Girdwood <lgirdwood@gmail.com>
Subject: Re: [PATCH v1 0/3] ASoC: Add bounds checking for written values
Date: Mon, 24 Jan 2022 16:52:46 +0000	[thread overview]
Message-ID: <Ye7ZXvIK3sVkvzQJ@sirena.org.uk> (raw)
In-Reply-To: <9eecf478-b705-7273-7553-24bafaec5404@perex.cz>

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On Mon, Jan 24, 2022 at 05:29:50PM +0100, Jaroslav Kysela wrote:
> On 24. 01. 22 16:32, Mark Brown wrote:

> > This series adds verification that values written to registers are in
> > bounds for controls since the core doesn't validate for us.

> As discussed, those conditions should be optional to eventually catch the
> wrong applications. I don't see any benefit to report the range error back
> when there is value masking code already. The users will note when the
> unwanted values are written to the hardware, or not?

In general I'd say that silent failures are harder to work with than
returning an error at the point where we notice that there's a problem,
assuming userspace is paying any attention to the error return at all of
course.  We certainly have quite a lot of existing put() methods that do
return errors and it's not like the application isn't invoking undefined
behaviour so I don't see a problem here.

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