Re: divide error: 0000 in the gspca_topro

[Mauro Carvalho Chehab <mchehab@osg.samsung.com>]

Em Mon, 09 Feb 2015 10:23:48 +0000
Luis de Bethencourt <luis@debethencourt.com> escreveu:

> On Sun, Feb 08, 2015 at 06:07:45PM -0800, Linus Torvalds wrote:
> > I got this, and it certainly seems relevant,.
> > 
> > It would seem that that whole 'quality' thing needs some range
> > checking, it should presumably be in the range [1..100] in order to
> > avoid negative 'sc' values or the divide-by-zero.
> > 
> > Hans, Mauro?
> > 
> >                       Linus
> 
> Hello Linus,
> 
> The case of quality being set to 0 is correctly handled in
> drivers/media/usb/gspca/jpeg.h [0], so I have sent a patch to do the same
> in topro.c.

Patch looks good to me.

I'll double check if some other driver has the same bad handling for
quality set and give a couple days for Hans to take a look.

If he's fine with this approach, I'll add it on a separate pull request.

Regards,
Mauro

> 
> Thanks,
> Luis
> 
> [0] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/media/usb/gspca/jpeg.h#n157
> 
> > 
> > ---------- Forwarded message ----------
> > From: Peter Kovář <peter.kovar@reflexion.tv>
> > Date: Sun, Feb 8, 2015 at 2:18 PM
> > Subject: divide error: 0000 in the gspca_topro
> > To: Linus Torvalds <torvalds@linux-foundation.org>
> > 
> > 
> > Hi++ Linus!
> > 
> > There is a trivial bug in the gspca_topro webcam driver.
> > 
> > /* set the JPEG quality for sensor soi763a */
> > static void jpeg_set_qual(u8 *jpeg_hdr,
> >                           int quality)
> > {
> >         int i, sc;
> > 
> >         if (quality < 50)
> >                 sc = 5000 / quality;
> >         else
> >                 sc = 200 - quality * 2;
> > 
> > 
> > 
> > Crash can be reproduced by setting JPEG quality to zero in the guvcview
> > application.
> > 
> > Cheers,
> > 
> > Peter Kovář
> > 50 65 74 65 72 20 4B 6F 76 C3 A1 C5 99
> > --
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