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zutruth

Member

Registered: 2017-10-08

Posts: 15

Webcam crashes irregularly on access

At times, when accessing my webcam device `/dev/video0` via `mpv`, `ffplay` or applications like Zoom, the webcam stops being responsive and causes a kernel null pointer deference. With this, the video devices `/dev/video0` and `/dev/video1` corresponding to the webcam vanish and the webcam isn’t recognized by the operating system anymore, even when manually replugging the webcam. I need to reboot my machine – however this is only possible by manually pressing poweroff on my machine – it seems the kernel cannot shut down properly.

Here s my `dmesg` output:

[May19 21:45] gdbus[1884]: segfault at 0 ip 00007f29beadfdf0 sp 00007f29bd6405f0 error 4 in libc-2.33.so[7f29bea83000+14c000]
[  +0.000009] Code: 00 48 c7 45 50 00 00 00 00 e9 80 ff ff ff 0f 1f 40 00 48 89 ef e8 60 fd ff ff 48 8b 45 08 48 3b 45 10 0f 83 4f ff ff ff 66 90 <0f> b6 00 48 83 c4 08 5b 5d c3 66 0f 1f 44 00 00 48 89 ef e8 98 fd
[May19 21:50] usb 3-3: USB disconnect, device number 7
[  +5.025753] BUG: kernel NULL pointer dereference, address: 0000000000000000
[  +0.000004] #PF: supervisor read access in kernel mode
[  +0.000001] #PF: error_code(0x0000) - not-present page
[  +0.000001] PGD 0 P4D 0 
[  +0.000003] Oops: 0000 [#1] SMP PTI
[  +0.000002] CPU: 0 PID: 2294 Comm: read_thread Not tainted 5.10.34-1-lts #1
[  +0.000001] Hardware name: LENOVO 10AAS36E00/SHARKBAY, BIOS FBKTA1AUS 10/22/2014
[  +0.000005] RIP: 0010:usb_ifnum_to_if+0x3a/0x50
[  +0.000002] Code: 34 41 0f b6 50 04 84 d2 74 2f 83 ea 01 49 8d 80 98 00 00 00 49 8d 8c d0 a0 00 00 00 eb 09 48 83 c0 08 48 39 c8 74 12 4c 8b 00 <49> 8b 10 0f b6 52 02 39 f2 75 e9 4c 89 c0 c3 45 31 c0 4c 89 c0 c3
[  +0.000001] RSP: 0018:ffffa07c419dbbc0 EFLAGS: 00010206
[  +0.000002] RAX: ffff8dbf27683498 RBX: 0000000000000000 RCX: ffff8dbf276834b8
[  +0.000001] RDX: 0000000000000003 RSI: 0000000000000001 RDI: ffff8dbf0d2ba000
[  +0.000001] RBP: ffff8dbf2edc9480 R08: 0000000000000000 R09: 0000000000000000
[  +0.000001] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8dbf27682c00
[  +0.000001] R13: ffff8dbf2edc9480 R14: ffff8dbf0d2ba000 R15: ffff8dbec66ae000
[  +0.000002] FS:  00007efe3f7fe640(0000) GS:ffff8dc1cea00000(0000) knlGS:0000000000000000
[  +0.000001] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  +0.000001] CR2: 0000000000000000 CR3: 00000001994f8006 CR4: 00000000001706f0
[  +0.000001] Call Trace:
[  +0.000004]  usb_hcd_alloc_bandwidth+0x23d/0x360
[  +0.000004]  usb_set_interface+0x123/0x360
[  +0.000006]  uvc_video_start_transfer+0x19c/0x4f0 [uvcvideo]
[  +0.000003]  uvc_video_start_streaming+0x7b/0xd0 [uvcvideo]
[  +0.000003]  uvc_start_streaming+0x2a/0xe0 [uvcvideo]
[  +0.000004]  vb2_start_streaming+0x63/0x100 [videobuf2_common]
[  +0.000003]  vb2_core_streamon+0x54/0xb0 [videobuf2_common]
[  +0.000003]  uvc_queue_streamon+0x2a/0x40 [uvcvideo]
[  +0.000002]  uvc_ioctl_streamon+0x3a/0x60 [uvcvideo]
[  +0.000009]  __video_do_ioctl+0x3ba/0x3f0 [videodev]
[  +0.000007]  video_usercopy+0x18e/0x610 [videodev]
[  +0.000004]  ? v4l_print_control+0x20/0x20 [videodev]
[  +0.000005]  v4l2_ioctl+0x48/0x50 [videodev]
[  +0.000003]  __x64_sys_ioctl+0x83/0xb0
[  +0.000002]  do_syscall_64+0x33/0x40
[  +0.000003]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  +0.000002] RIP: 0033:0x7efe4e9e9e6b
[  +0.000002] Code: ff ff ff 85 c0 79 8b 49 c7 c4 ff ff ff ff 5b 5d 4c 89 e0 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d d5 af 0c 00 f7 d8 64 89 01 48
[  +0.000001] RSP: 002b:00007efe3f7fd0a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[  +0.000001] RAX: ffffffffffffffda RBX: 00007efe100019c0 RCX: 00007efe4e9e9e6b
[  +0.000001] RDX: 00007efe3f7fd0e8 RSI: 0000000040045612 RDI: 000000000000000d
[  +0.000001] RBP: 00007efe10000c80 R08: 000000000000000d R09: 000000000367e000
[  +0.000001] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000047504a4d
[  +0.000001] R13: 00007efe100019c0 R14: 0000000000000007 R15: 00007efe3f7fd0e8
[  +0.000002] Modules linked in: uas usb_storage 8021q garp mrp stp llc ccm wacom joydev mousedev uvcvideo btusb btrtl btbcm videobuf2_vmalloc btintel videobuf2_memops snd_usb_audio bluetooth videobuf2_v4l2 videobuf2_common snd_usbmidi_lib videodev ecdh_generic snd_rawmidi ecc snd_seq_device usbhid mc crc16 snd_hda_codec_hdmi intel_rapl_msr intel_rapl_common snd_hda_codec_realtek snd_hda_codec_generic iwlmvm ledtrig_audio snd_hda_intel x86_pkg_temp_thermal mac80211 snd_intel_dspcfg intel_powerclamp soundwire_intel coretemp mei_wdt iTCO_wdt intel_pmc_bxt soundwire_generic_allocation soundwire_cadence libarc4 at24 snd_hda_codec mei_hdcp iTCO_vendor_support wmi_bmof i915 iwlwifi rapl snd_hda_core snd_hwdep intel_cstate soundwire_bus i2c_algo_bit intel_uncore pcspkr cfg80211 snd_soc_core drm_kms_helper snd_compress ac97_bus rfkill snd_pcm_dmaengine cec snd_pcm intel_gtt syscopyarea sysfillrect e1000e snd_timer sysimgblt mei_me tpm_tis fb_sys_fops snd mei video i2c_i801 tpm_tis_core soundcore
[  +0.000047]  mac_hid lpc_ich i2c_smbus wmi drm sg fuse crypto_user agpgart bpf_preload ip_tables x_tables dm_crypt cbc encrypted_keys dm_mod trusted tpm rng_core btrfs blake2b_generic crct10dif_pclmul libcr

Here, the webcam crashed at 21:50. The segfault before seems unrelated, but I included it for completeness.

Does anyone have any idea how to handle this?

My system is up-to-date. I’m on linux-lts right now, but this happens on regular linux as well:
`Linux 5.10.34-1-lts #1 SMP Sun, 02 May 2021 12:41:09 +0000 GNU/Linux`
Oh, and this has been occuring since at least September 2020, but it’s happening irregularly and has gotten worse. (So maybe my webcam has just become garbage?)

Last edited by zutruth (2021-05-19 20:07:22)

morganfshirley

Member

Registered: 2013-01-31

Posts: 3

Re: Webcam crashes irregularly on access

In case someone stumbles upon this thread while troubleshooting (as I did): I had the same set of issues and was able to resolve them by loading the uvcvideo driver with quirks=0x100, similar to the wiki instructions on how to fix Microsoft Lifecam.