On Thu, Sep 29, 2022 at 06:53:46PM +0000, bugzilla-daemon@xxxxxxxxxx wrote: > With a flaky USB 3.0 cable (3m extension + 2m cable + 90 degree adapter) and > Logitech BRIO webcam I got exactly the same null pointer dereference twice > already. That's really an unstable and unsupported system, sorry. If you fix your cable it should work properly, right? > Here are two instances (from different boots): > [64977.148098] BUG: kernel NULL pointer dereference, address: 0000000000000000 > [64977.148101] #PF: supervisor read access in kernel mode > [64977.148102] #PF: error_code(0x0000) - not-present page > [64977.148103] PGD 101370067 P4D 101370067 PUD 0 > [64977.148105] Oops: 0000 [#1] SMP NOPTI > [64977.148107] CPU: 14 PID: 27951 Comm: VideoCapture Not tainted > 5.19.10-xanmod1-x64v2 #0~20220920.git017c598 What about any kernel log messages from right before this crashed? There should be some disconnect or other USB messages, right? Specifics here would be good to see. > [64977.148109] Hardware name: Gigabyte Technology Co., Ltd. B550 VISION D/B550 > VISION D, BIOS F15d 07/20/2022 > [64977.148109] RIP: 0010:usb_ifnum_to_if+0x34/0x60 > [64977.148113] Code: 74 33 0f b6 4a 04 84 c9 74 33 83 e9 01 48 8d 82 98 00 00 > 00 48 8d bc ca a0 00 00 00 eb 09 48 83 c0 08 48 39 f8 74 16 48 8b 10 <48> 8b 0a > 0f b6 49 02 39 f1 75 e9 48 89 d0 c3 cc cc cc cc 31 d2 48 > [64977.148114] RSP: 0018:ffffb20951407bb0 EFLAGS: 00010202 > [64977.148115] RAX: ffff8cfbbc618098 RBX: ffff8ceb844cc800 RCX: > 0000000000000004 > [64977.148116] RDX: 0000000000000000 RSI: 0000000000000001 RDI: > ffff8cfbbc6180c0 > [64977.148117] RBP: 0000000000000000 R08: 0000000080000000 R09: > ffffffff8f590de8 > [64977.148117] R10: 0000000000000001 R11: 0000000000000001 R12: > ffff8cf67c70f398 > [64977.148118] R13: 0000000000000000 R14: ffff8cf67c70f208 R15: > ffff8ceb8123c000 > [64977.148119] FS: 00007f5f51379640(0000) GS:ffff8d0a3ed80000(0000) > knlGS:0000000000000000 > [64977.148120] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [64977.148120] CR2: 0000000000000000 CR3: 000000023b842000 CR4: > 0000000000750ee0 > [64977.148121] PKRU: 55555554 > [64977.148122] Call Trace: > [64977.148123] <TASK> > [64977.148124] usb_hcd_alloc_bandwidth+0x241/0x360 > [64977.148127] usb_set_interface+0x11d/0x340 > [64977.148130] uvc_video_start_transfer+0x17b/0x4b0 [uvcvideo] This isn't good, we shouldn't crash when a device is removed, but this might be an issue with some reference counting. More log messages might help out here. thanks, greg k-h
