Re: [PATCH] iio: core: fix uninitialized data in debugfs

On Mon, May 25, 2026 at 11:13 AM Dan Carpenter <[email protected]> wrote:
>
> On Mon, May 25, 2026 at 08:17:28AM -0500, Maxwell Doose wrote:
> > Hi Dan,
> >
> > On Mon, May 25, 2026 at 2:19 AM Dan Carpenter <[email protected]> wrote:
> > >
> > > If *ppos is non-zero then simple_write_to_buffer() will not initialize
> > > the start of buf[].  Non zero values for *ppos aren't going to work
> > > anyway.  Test for them at the start of the function and return -EINVAL.
> > >
> > > Fixes: 6d5dd486c715 ("iio: core: make use of simple_write_to_buffer()")
> > > Signed-off-by: Dan Carpenter <[email protected]>
> > > ---
> > > The original copy_from_user() code was better:
> > > https://staticthinking.wordpress.com/2026/05/23/simple_write_to_buffer-is-complicated/
> > > ---
> > >  drivers/iio/industrialio-core.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> >
> > Codewise looks good but often times people will prefer
> >
> > if (*ppos || count >= sizeof(buf))
> >
> > over
> >
> > if (*ppos != 0 || count >= sizeof(buf))
>
> In this context, I feel like either is acceptable since zero
> represents the number zero.  I have a blog about that which I have
> been trying to promote.  #SEO
>
> https://staticthinking.wordpress.com/2024/02/20/when-to-use-0/
>

Interesting article, and I do agree that either is appropriate, just
wanted to give you a heads up in case Jonathan or Andy ask you to
change it.

best regards,
max


>
> >
> > Regardless,
> >
> > Reviewed-by: Maxwell Doose <[email protected]>
> >
>
> Thanks.  And you're other comments with regards to -EINVAL and
> -ENOSPC are obviously correct.
>
> regards,
> dan carpenter
>