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

[Dan Carpenter <error27@gmail.com>]

On Thu, Jun 04, 2026 at 10:30:34AM +0300, Andy Shevchenko wrote:
> On Tue, May 26, 2026 at 07:19:46PM +0100, Jonathan Cameron wrote:
> > On Mon, 25 May 2026 08:20:31 -0500
> > Maxwell Doose <m32285159@gmail.com> wrote:
> > > On Mon, May 25, 2026 at 2:17 AM Dan Carpenter <error27@gmail.com> wrote:
> > > >
> > > > If the *ppos value is non-zero then simple_write_to_buffer() will not
> > > > initialize the start of the buf[] buffer.  Non-zero ppos values aren't
> > > > going to work at all.  Check for that at the start of the function and
> > > > return -EINVAL.
> > > 
> > > Commit message is incorrect, it looks like you're returning -ENOSPC here...
> > Tweaked and applied to the fixes-togreg branch of iio.git + marked for stable.
> 
> I was stumbled over these patches by Dan. Since the file_operations for the code
> in question do not define .llseek, the seek is not supported and will return
> -ESPIPE. I'm not sure why we have these patches to begin with. Dan, can you
> elaborate on the case where the *ppos is not 0, please?

The simple_write_to_buffer() will update *ppos so partial writes are
supported in that way.

regards,
dan carpenter