The change in 8280b66 does not cover the case when v4l2_dev is already NULL, fix that. With a Kinect sensor, seen as an USB camera using GSPCA in this context, a NULL pointer dereference BUG can be triggered by just unplugging the device after the camera driver has been loaded. Signed-off-by: Antonio Ospite <ospite@xxxxxxxxxxxxxxxxx> --- Hi, can anyone reproduce this? This is the complete trace, I left it out of the commit message, but feel free to include it if you think it is worth it. BUG: unable to handle kernel NULL pointer dereference at 0000000000000090 IP: [<ffffffffa10cc604>] v4l2_device_release+0xb8/0xe8 [videodev] PGD 0 Oops: 0000 [#1] SMP CPU 0 Modules linked in: snd_usb_audio snd_usbmidi_lib gspca_kinect gspca_main videodev media v4l2_compat_ioctl32 hidp snd_hrtimer ebtable_nat ebtables powernow_k8 mperf cpufreq_powersave cpufreq_conservative cpufreq_stats cpufreq_userspace ipt_MASQUERADE xt_CHECKSUM bridge stp ppdev lp bnep rfcomm tun sit tunnel4 ip6table_raw ip6table_mangle ip6t_REJECT ip6t_LOG nf_conntrack_ipv6 nf_defrag_ipv6 ip6t_rt ip6table_filter ip6_tables decnet binfmt_misc uinput fuse xt_tcpudp ipt_REJECT ipt_ULOG xt_limit xt_state xt_multiport iptable_filter iptable_nat nf_nat nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 iptable_mangle iptable_raw ip_tables x_tables nfsd nfs lockd fscache auth_rpcgss nfs_acl sunrpc it87 hwmon_vid loop kvm_amd kvm snd_hda_codec_hdmi snd_hda_codec_via nvidia(P) snd_hda_intel snd_hda_codec snd_hwdep snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_midi snd_rawmidi cryptd aes_x86_64 snd_seq_midi_event aes_generic ecb snd_seq btusb bluetooth evdev snd_timer snd_seq_device edac_core parport_pc pcspkr parport rfkill snd edac_mce_amd k8temp crc16 soundcore mxm_wmi snd_page_alloc asus_atk0110 shpchp video pci_hotplug i2c_nforce2 wmi i2c_core processor thermal_sys button ext3 jbd mbcache dm_mod sg sd_mod sr_mod crc_t10dif cdrom ata_generic usb_storage usbhid hid uas ahci libahci pata_amd libata scsi_mod forcedeth floppy ohci_hcd ehci_hcd usbcore [last unloaded: scsi_wait_scan] Pid: 125, comm: khubd Tainted: P 3.1.0-rc9-ao2 #3 System manufacturer System Product Name/M3N78-VM RIP: 0010:[<ffffffffa10cc604>] [<ffffffffa10cc604>] v4l2_device_release+0xb8/0xe8 [videodev] RSP: 0018:ffff88011639fc10 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8800ca61a088 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffffa10db000 RBP: 0000000000000000 R08: ffffffff8119b320 R09: ffffffff8119b320 R10: 0000000000000001 R11: 0000000000000001 R12: ffff8800ca61a000 R13: ffffffff8164ffb0 R14: 0000000000000000 R15: 000000000000001f FS: 00007f61275f37a0(0000) GS:ffff88011fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000090 CR3: 00000001150de000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process khubd (pid: 125, threadinfo ffff88011639e000, task ffff88011639d590) Stack: ffff8800ca5d8380 ffff8800ca61a098 ffff8800ca66c200 ffffffff81232e94 ffff8800ca61a0d0 ffffffff8119a7fa ffffffff8119b320 ffff8800ca61a0d0 ffffffff8119a7ab ffff8800ca56dc00 ffffffffa10e1068 ffffffff8119b93a Call Trace: [<ffffffff81232e94>] ? device_release+0x41/0x72 [<ffffffff8119a7fa>] ? kobject_release+0x4f/0x6c [<ffffffff8119b320>] ? add_uevent_var+0xdc/0xdc [<ffffffff8119a7ab>] ? kobject_del+0x2d/0x2d [<ffffffff8119b93a>] ? kref_put+0x3e/0x47 [<ffffffffa0039f15>] ? usb_unbind_interface+0x4d/0x111 [usbcore] [<ffffffff81235b9b>] ? __device_release_driver+0x7d/0xc9 [<ffffffff81235c02>] ? device_release_driver+0x1b/0x27 [<ffffffff81235804>] ? bus_remove_device+0x7c/0x8b [<ffffffff812337e6>] ? device_del+0x129/0x177 [<ffffffffa00384f7>] ? usb_disable_device+0x6a/0x159 [usbcore] [<ffffffffa003250c>] ? usb_disconnect+0x8c/0x108 [usbcore] [<ffffffffa00324ed>] ? usb_disconnect+0x6d/0x108 [usbcore] [<ffffffffa0033bc5>] ? hub_thread+0x58e/0xec6 [usbcore] [<ffffffff81036e08>] ? set_next_entity+0x32/0x52 [<ffffffff8105ec53>] ? add_wait_queue+0x3c/0x3c [<ffffffffa0033637>] ? usb_remote_wakeup+0x2f/0x2f [usbcore] [<ffffffff8105e60d>] ? kthread+0x76/0x7e [<ffffffff81332f34>] ? kernel_thread_helper+0x4/0x10 [<ffffffff8105e597>] ? kthread_worker_fn+0x139/0x139 [<ffffffff81332f30>] ? gs_change+0x13/0x13 Code: 0d a1 e8 7a ec 25 e0 48 8b 83 78 02 00 00 48 85 c0 74 18 48 83 78 08 00 74 11 83 bb b0 02 00 00 03 74 08 4c 89 e7 e8 03 5a ff ff 83 bd 90 00 00 00 00 b8 00 00 00 00 4c 89 e7 48 0f 44 e8 ff RIP [<ffffffffa10cc604>] v4l2_device_release+0xb8/0xe8 [videodev] RSP <ffff88011639fc10> CR2: 0000000000000090 ---[ end trace 99f7feddc91f30d6 ]--- Thanks, Antonio Ospite http://ao2.it drivers/media/video/v4l2-dev.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c index d721565..a5c9ed1 100644 --- a/drivers/media/video/v4l2-dev.c +++ b/drivers/media/video/v4l2-dev.c @@ -181,7 +181,7 @@ static void v4l2_device_release(struct device *cd) * TODO: In the long run all drivers that use v4l2_device should use the * v4l2_device release callback. This check will then be unnecessary. */ - if (v4l2_dev->release == NULL) + if (v4l2_dev && v4l2_dev->release == NULL) v4l2_dev = NULL; /* Release video_device and perform other -- 1.7.7 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
