Fwd: I have problem with libv4l

[Alex V. Petrov]

2011/9/4 Hans de Goede <hdegoede at redhat.com>

> Hi,
>
> On 08/31/2011 02:18 PM, Hans Petter Selasky wrote:
>
>>
>> ----------  Forwarded Message  ----------
>>
>> Subject: I have problem with libv4l
>> Date: Wednesday 31 August 2011, 13:44:37
>> From: "Alex V. Petrov"<alexvpetrov at gmail.com>
>> To: freebsd-multimedia at freebsd.org
>> CC: hselasky at freebsd.org
>>
>> Hi all!
>>
>> In June, after updating libv4l, my webcam (Mustek Gsmart mini 3) is not
>> working (I use pwcview).
>>
>> $ pwcview
>> Webcam set to: 320x240 (sif) at 5 fps
>> Segmentation fault (core dumped)
>>
>> gdb:
>> #0  0x0000000800ae1bfb in jpeg_idct_16x16 (cinfo=Variable "cinfo" is not
>> available.) at jidctint.c:2760
>> 2760        outptr[0]  = range_limit[(int) RIGHT_SHIFT(tmp20 + tmp0,
>> [New Thread 803807400 (LWP 101450/pwcview)]
>>
>
> Hmm, this points to a bug in libjpeg, since recent versions of libv4l
> have switched to using libjpeg for jpeg decompression, because of speed
> reasons, except for some special cases (because some cams produce non
> standard compliant JPEG data and the tinyjpeg copy bundled with libv4l
> contains several patches to deal with this).
>
> Can you tell me the usb-id / chipset of your camera, so that I can
> try to reproduce? I likely won't be able to reproduce though. What
> version of libjpeg are you using, and with which compiler is it
> build ?
>
> Can you perhaps try to reproduce this under Linux? Preferably
> Fedora 15?
>
> There are 2 solutions to this problem:
> 1) If it is specific to this webcam / chipset, add a quirk to libv4l's
> quirk table to use the embedded tinyjpeg copy
>
> 2) Figure out what is causing libjpeg to crash and fix it.
>
>
> With 2 being preferable since a segfault inside libjpeg (assuming it
> is not the way libv4l uses libjpeg for now), does smell like a security
> issue to me.
>
> Regards,
>
> Hans
>

ugen0.2: <product 0xc520 vendor 0x055f> at usbus0, cfg=0 md=HOST spd=FULL
(12Mbps) pwr=ON

jpeg-8_3 with cc (GCC) 4.2.2 20070831 prerelease [FreeBSD]

Fedora 15 will try later.

-- 
----------------------
Alex V. Petrov