Re: [kbuild-all] Re: [PATCH] coccinelle: api: fix device_attr_show.cocci warnings

[Julia Lawall <julia.lawall@inria.fr>]

On Tue, 8 Sep 2020, Bartlomiej Zolnierkiewicz wrote:

>
> Hi,
>
> On 8/10/20 11:21 AM, kernel test robot wrote:
> > From: kernel test robot <lkp@intel.com>
> >
> > drivers/video/fbdev/core/fbcon.c:3509:8-16: WARNING: use scnprintf or sprintf
> > drivers/video/fbdev/core/fbcon.c:3484:8-16: WARNING: use scnprintf or sprintf
> >
> >
> >  From Documentation/filesystems/sysfs.txt:
> >   show() must not use snprintf() when formatting the value to be
> >   returned to user space. If you can guarantee that an overflow
> >   will never happen you can use sprintf() otherwise you must use
> >   scnprintf().
> >
> > Generated by: scripts/coccinelle/api/device_attr_show.cocci
> >
> > Fixes: abfc19ff202d ("coccinelle: api: add device_attr_show script")
> > CC: Denis Efremov <efremov@linux.com>
> > Signed-off-by: kernel test robot <lkp@intel.com>
> > ---
> >
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head:   fc80c51fd4b23ec007e88d4c688f2cac1b8648e7
> > commit: abfc19ff202d287742483e15fd478ddd6ada2187 coccinelle: api: add device_attr_show script
> >
> > Please take the patch only if it's a positive warning. Thanks!
> >
> >  fbcon.c |    4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > --- a/drivers/video/fbdev/core/fbcon.c
> > +++ b/drivers/video/fbdev/core/fbcon.c
> > @@ -3481,7 +3481,7 @@ static ssize_t show_rotate(struct device
> >  	rotate = fbcon_get_rotate(info);
> >  err:
> >  	console_unlock();
> > -	return snprintf(buf, PAGE_SIZE, "%d\n", rotate);
> > +	return scnprintf(buf, PAGE_SIZE, "%d\n", rotate);
>
> buf length is at least PAGE_SIZE and rotate val is an int so
> shouldn't this be converted to use sprintf() instead?

The rule is evolving in this direction.  Thanks for the feedback.

julia

>
> >  }
> >
> >  static ssize_t show_cursor_blink(struct device *device,
> > @@ -3506,7 +3506,7 @@ static ssize_t show_cursor_blink(struct
> >  	blink = (ops->flags & FBCON_FLAGS_CURSOR_TIMER) ? 1 : 0;
> >  err:
> >  	console_unlock();
> > -	return snprintf(buf, PAGE_SIZE, "%d\n", blink);
> > +	return scnprintf(buf, PAGE_SIZE, "%d\n", blink);
>
> ditto for blink val
>
> >  }
> >
> >  static ssize_t store_cursor_blink(struct device *device,
> >
>
> Best regards,
> --
> Bartlomiej Zolnierkiewicz
> Samsung R&D Institute Poland
> Samsung Electronics
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