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Date: Mon, 9 Feb 2015 10:23:48 +0000
From: Luis de Bethencourt <luis@debethencourt.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hans de Goede <hdegoede@redhat.com>,
	Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
	Linux Media Mailing List <linux-media@vger.kernel.org>
Subject: Re: Fwd: divide error: 0000 in the gspca_topro
Message-ID: <20150209102348.GB28420@biggie>
References: <54D7E0B8.30503@reflexion.tv>
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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.

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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