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

On Mon, 25 May 2026 08:20:31 -0500
Maxwell Doose <[email protected]> wrote:

> On Mon, May 25, 2026 at 2:17 AM Dan Carpenter <[email protected]> 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.

thanks,

J
> 
> >
> > Fixes: cdf01e0809a4 ("iio: backend: add debugFs interface")
> > Signed-off-by: Dan Carpenter <[email protected]>
> > ---
> >  drivers/iio/industrialio-backend.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
> > index 138ebebc9c0d..4763e224ebc6 100644
> > --- a/drivers/iio/industrialio-backend.c
> > +++ b/drivers/iio/industrialio-backend.c
> > @@ -156,7 +156,7 @@ static ssize_t iio_backend_debugfs_write_reg(struct file *file,
> >         ssize_t rc;
> >         int ret;
> >
> > -       if (count >= sizeof(buf))
> > +       if (*ppos != 0 || count >= sizeof(buf))
> >                 return -ENOSPC;
> >  
> 
> See above comment.
> 
> best regards,
> max
> 
> 
> >
> >         rc = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, userbuf, count);
> > --
> > 2.53.0
> >
> >