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

On Mon, 25 May 2026 15:08:14 -0500
Maxwell Doose <[email protected]> wrote:

> 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
> 
Applied to the fixes-togreg branch of iio.git and marked for stable.

Thanks,

Jonathan

> >  
> > >
> > > 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
> >