Re: [PATCH] Input: wacom_w8001: Check for string overflow from strscpy calls

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Mon, May 20, 2024 at 08:55:30PM -0700, Ping Cheng wrote:
> On Mon, May 20, 2024 at 4:28 PM Dmitry Torokhov
> <dmitry.torokhov@gmail.com> wrote:
> 
> Hi Dmitry,
> 
> > > This fix is the same as [1]. Without checking the return value,
> > > Wolfram's patch [2] fails our downstream build script. I'm adding my
> > > r-b, if it makes any difference ;).
> >
> > Could you please tell me how exactly it makes your build script to fail?
> 
> We got an "unused-result warning". Jason made a temporary workaround
> at https://github.com/linuxwacom/input-wacom/commit/e83a9bb3e48d2d1b52ec709e60f73b9960d568e5.

I do not think strscpy is declared as __must_check. Do you have a repro
for the vanilla kernel build?

> 
> > My concern is that the warnings are not actionable and therefore pretty
> > much worthless.
> 
> The return value tells us which strscpy call(s) didn't have enough space.

Right, and what can be done about it? The driver does not control what
tty is being used for the serial port (and so can't control the prefix
of the 'phys'), we do not extend 'phys' (because it is used very
rarely). The only option is to truncate (which we already do).

So the warnings are not actionable.

Thanks.

-- 
Dmitry