Fwd: I have problem with libv4l
Alex V. Petrov
alexvpetrov at gmail.com
Mon Sep 5 01:40:42 UTC 2011
2011/9/4 Hans de Goede <hdegoede at redhat.com>
> 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)
>> #0 0x0000000800ae1bfb in jpeg_idct_16x16 (cinfo=Variable "cinfo" is not
>> available.) at jidctint.c:2760
>> 2760 outptr = 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.
ugen0.2: <product 0xc520 vendor 0x055f> at usbus0, cfg=0 md=HOST spd=FULL
jpeg-8_3 with cc (GCC) 4.2.2 20070831 prerelease [FreeBSD]
Fedora 15 will try later.
Alex V. Petrov
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