0471:0311 BUG: unable to handle kernel NULL pointer dereference at 0000000000000050; RIP: 0010:[<ffffffffa0112d6e>] [<ffffffffa0112d6e>] v4l2_ctrl_s_ctrl+0xe/0x50 [videodev]

[astro]

Since Ubuntu 12.04,

I get a kernel oops when trying to use the Toucam Pro 2 Philips USB webcam with Qastrocam-g2 (not part of Ubuntu repos) an astronomy program that use advanced functions of Philips webcam. Basic usage of the webcam with cheese is still possible.

It used to work well before.

On AMD64x2 desktop/Ubuntu 12.04 Desktop x86-64, I installed:
- libqwtplot3d-qt3-0_0.2.7+svn191-4_amd64.deb (http://pkgs.org/debian-sid)
- qastrocam-g2_4.8_amd64.deb (sourceforge)
I plug in the Philips Toucam Pro 2 USB webcam.
I run qastrocam-g2, configure it to use the V4L2 device associated with the Philips Toucam Pro 2 USB webcam in the setting tabs and restart the program. I get a oops and the system hangs.

Maybe this is the fix (?):
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ceede9fa8939e40ad0ddb4ad1355f45c6f1d3478

UNAME A for AMD64x2 desktop
Linux saturn 3.2.0-24-generic #39-Ubuntu SMP Mon May 21 16:52:17 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

I have tested the latest mainline kernel packaged for precise:
linux-image-3.4.0-030400rc6-generic_3.4.0-030400rc6.201205061835_amd64.deb

Note that this package is dated 06-May-2012 and this git commit http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ceede9fa8939e40ad0ddb4ad1355f45c6f1d3478 is from 09-May-2012, so this kernel doesn't contain the latest fix(es) on the PWC driver.

With this kernel, I don't get a OOPS with qastrocam-g2 and qastrocam-g2 can acquire pictures from the Toucam Pro 2.
However, most IOCTL commands used by qastrocam-g2 to set camera parameters such as the gain are not recognized (see attached console output). This was not the case in older version of Ubuntu such as 11.10. Interestingly the file drivers/media/video/pwc/pwc-ioctl.h was removed after kernel 3.0 ( http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git&a=search&h=HEAD&st=commit&s=pwc-ioctl ) because it was redundant? with include/media/pwc-ioctl.h.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.2.0-24-generic 3.2.0-24.39
ProcVersionSignature: Ubuntu 3.2.0-24.39-generic 3.2.16
Uname: Linux 3.2.0-24-generic x86_64
NonfreeKernelModules: nvidia
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu8
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC2: astro 2096 F.... pulseaudio
 /dev/snd/controlC0: astro 2096 F.... pulseaudio
 /dev/snd/controlC1: astro 2096 F.... pulseaudio
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
Card0.Amixer.info:
 Card hw:0 'NVidia'/'HDA NVidia at 0xfe020000 irq 20'
   Mixer name : 'Realtek ALC883'
   Components : 'HDA:10ec0883,147b8e01,00100002'
   Controls : 48
   Simple ctrls : 23
Card1.Amixer.info:
 Card hw:1 'CX8811'/'Conexant CX8811 at 0xfa000000'
   Mixer name : 'CX88'
   Components : ''
   Controls : 4
   Simple ctrls : 3
Card2.Amixer.info:
 Card hw:2 'U0x4710x311'/'USB Device 0x471:0x311 at usb-0000:00:02.1-2.2, full speed'
   Mixer name : 'USB Mixer'
   Components : 'USB0471:0311'
   Controls : 2
   Simple ctrls : 1
Card2.Amixer.values:
 Simple mixer control 'Mic',0
   Capabilities: cvolume cvolume-joined cswitch cswitch-joined penum
   Capture channels: Mono
   Limits: Capture 0 - 3
   Mono: Capture 1 [33%] [40.00dB] [on]
Date: Thu Jun 7 13:21:09 2012
HibernationDevice: RESUME=UUID=7b300250-5947-480e-ae81-cbd4ae320b01
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
IwConfig:
 lo no wireless extensions.

 eth1 no wireless extensions.

 eth0 no wireless extensions.
ProcEnviron:
 TERM=xterm
 SHELL=/bin/bash
 PATH=(custom, no user)
 LANG=en_US.UTF-8
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-24-generic root=UUID=bb81248b-bffa-45bc-b89f-17801018eb28 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.2.0-24-generic N/A
 linux-backports-modules-3.2.0-24-generic N/A
 linux-firmware 1.79
RfKill:

SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/13/2006
dmi.bios.vendor: Phoenix Technologies, LTD
dmi.bios.version: 6.00 PG
dmi.board.name: KN9(NF-MCP55 series)
dmi.board.vendor: http://www.abit.com.tw/
dmi.board.version: 1.x
dmi.chassis.type: 3
dmi.modalias: dmi:bvnPhoenixTechnologies,LTD:bvr6.00PG:bd07/13/2006:svn:pn:pvr:rvnhttp//www.abit.com.tw/:rnKN9(NF-MCP55series):rvr1.x:cvn:ct3:cvr:

[penalvch (penalvch)]

Marking Triaged as mainline tested and Medium due to:
2012-06-07 15:42:40 Joseph Salisbury linux (Ubuntu): importance Undecided Medium

[penalvch (penalvch)]

astro, regarding your Bug Description:
>"It used to work well before."

What release did this used to work well in? Could you please elaborate on how well it worked? It crashed less often or not at all?

[astro (bernard-godard)]

> What release did this used to work well in? Could you please elaborate on how well it worked? It crashed less often or not at all?

I have used his webcam on different distributions with the same program qastrocam from at least 2007 to now. And this worked perfectly until 12.04. It works in 11.10. In 12.04 default desktop kernel, I get an oops. With the upstream kernel no oops, but the IOCTL are not recognized (this is because of the PWC V4L API upgrade which requires an upgrade of the qastrocam program).

[penalvch (penalvch)]

astro, this bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? If so, could you please test for this with the latest development release of Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-live/current/ .

If it remains an issue, please just make a comment to this.

If reproducible, could you also please test the latest upstream kernel available (not the daily folder) following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags:
kernel-fixed-upstream
kernel-fixed-upstream-VERSION-NUMBER

where VERSION-NUMBER is the version number of the kernel you tested. For example:
kernel-fixed-upstream-v3.13-rc6

This can be done by clicking on the yellow circle with a black pencil icon next to the word Tags located at the bottom of the bug description. As well, please remove the tag:
needs-upstream-testing

If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-VERSION-NUMBER

As well, please remove the tag:
needs-upstream-testing

Once testing of the upstream kernel is complete, please mark this bug's Status as Confirmed. Please let us know your results. Thank you for your understanding.

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]