On Mon, Nov 21, 2016 at 02:19:32PM +0100, Oliver Neukum wrote: > I don't understand it, bit please test the attached patch > with dynamic debugging for cdc-acm and the kernel log level > at maximum.
> diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c > index 6895f9e..f03b5db 100644 > --- a/drivers/usb/class/cdc-acm.c > +++ b/drivers/usb/class/cdc-acm.c > @@ -1188,6 +1188,12 @@ static int acm_probe(struct usb_interface *intf, > > cdc_parse_cdc_header(&h, intf, buffer, buflen); > union_header = h.usb_cdc_union_desc; > + > + dev_dbg(&intf->dev, "Parsed device header\n"); > + dev_dbg(&intf->dev, "Union descriptor %p\n", h.usb_cdc_union_desc); > + dev_dbg(&intf->dev, "ACM descriptor %p\n", h.usb_cdc_acm_descriptor); > + dev_dbg(&intf->dev, "Country descriptor %p\n", > h.usb_cdc_country_functional_desc); > + > cmgmd = h.usb_cdc_call_mgmt_descriptor; > if (cmgmd) > call_intf_num = cmgmd->bDataInterface; On kernel 4.8.8 this crashes hard and produces over a serial link: [ 156.842106] sysrq: SysRq : Changing Loglevel [ 156.842110] sysrq: Loglevel set to 9 [ 156.947852] usbcore: registered new interface driver cdc_acm [ 156.947854] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters [ 161.176701] usb 4-1: new full-speed USB device number 2 using uhci_hcd [ 161.383608] usb 4-1: New USB device found, idVendor=0572, idProduct=1340 [ 161.384707] usb 4-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 161.388722] usb 4-1: Product: USB Modem [ 161.392711] usb 4-1: Manufacturer: Conexant [ 161.392714] usb 4-1: SerialNumber: 12345678 [ 161.397703] cdc_acm:acm_probe: cdc_acm 4-1:1.0: interfaces are valid [ 161.397731] BUG: unable to handle kernel NULL pointer dereference at 00000249 [ 161.397740] IP: [<e086ad09>] acm_probe+0x580/0xd1e [cdc_acm] [ 161.397742] *pde = 00000000 [ 161.397745] Oops: 0000 [#1] SMP [ 161.397786] Modules linked in: cdc_acm radeon drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm agpgart i2c_algo_bit fbcon bitblit softcursor font tileblit binfmt_misc snd_pcm_oss snd_mixer_oss usb_storage usbhid ipw2200 libipw lib80211 snd_intel8x0 cfg80211 snd_ac97_codec ac97_bus uhci_hcd snd_pcm ehci_pci snd_timer snd ehci_hcd rfkill usbcore soundcore via_rhine firmware_class ppdev pcspkr parport_pc mii lpc_ich parport fan usb_common acpi_cpufreq thermal mfd_core floppy button processor [ 161.397790] CPU: 0 PID: 4 Comm: kworker/0:0 Not tainted 4.8.8 #2 [ 161.397792] Hardware name: MEDIONPC MS-7048/MS-7048, BIOS 6.00 PG 02/12/2004 [ 161.397805] Workqueue: usb_hub_wq hub_event [usbcore] [ 161.397807] task: df4c9500 task.stack: df4da000 [ 161.397810] EIP: 0060:[<e086ad09>] EFLAGS: 00010202 CPU: 0 [ 161.397813] EIP is at acm_probe+0x580/0xd1e [cdc_acm] [ 161.397815] EAX: 00000246 EBX: dc27b000 ECX: e086c934 EDX: 00000000 [ 161.397817] ESI: 00000100 EDI: 00000000 EBP: df4dbc18 ESP: df4dbb80 [ 161.397819] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 [ 161.397821] CR0: 80050033 CR2: 00000249 CR3: 1c45f000 CR4: 00000690 [ 161.397822] Stack: [ 161.397828] 00003640 00003662 0000000e df491d50 00000000 00000000 00000010 00000040 [ 161.397835] 00000080 00000246 dd1fc540 decf5a00 dc468c70 00000001 df583a00 df583a38 [ 161.397841] dc468c00 decf5800 decf5a00 00000000 dc452ab0 00000004 00000246 df4dbc00 [ 161.397842] Call Trace: [ 161.397853] [<c04bce4d>] ? __mutex_unlock_slowpath+0xf4/0xfc [ 161.397862] [<e1e2e50d>] ? usb_probe_interface+0x17b/0x1f6 [usbcore] [ 161.397870] [<e1e2e50d>] ? usb_probe_interface+0x17b/0x1f6 [usbcore] [ 161.397877] [<c0366fe8>] ? driver_probe_device+0x17b/0x30e [ 161.397880] [<c0366fe8>] ? driver_probe_device+0x17b/0x30e [ 161.397883] [<c03656e2>] ? bus_for_each_drv+0x59/0x68 [ 161.397886] [<c03656e2>] ? bus_for_each_drv+0x59/0x68 [ 161.397890] [<c0366d96>] ? __device_attach+0x91/0x105 [ 161.397893] [<c036727c>] ? driver_allows_async_probing+0x2f/0x2f [ 161.397896] [<c036636a>] ? bus_probe_device+0x27/0x6b [ 161.397899] [<c036636a>] ? bus_probe_device+0x27/0x6b [ 161.397902] [<c0364af0>] ? device_add+0x289/0x4be [ 161.397911] [<e1e2ce72>] ? usb_set_configuration+0x5a6/0x5e9 [usbcore] [ 161.397919] [<e1e2ce72>] ? usb_set_configuration+0x5a6/0x5e9 [usbcore] [ 161.397928] [<e1e34664>] ? generic_probe+0x3b/0x67 [usbcore] [ 161.397937] [<e1e34664>] ? generic_probe+0x3b/0x67 [usbcore] [ 161.397945] [<e1e2e379>] ? usb_probe_device+0x49/0x62 [usbcore] [ 161.397953] [<e1e2e330>] ? usb_suspend+0xcd/0xcd [usbcore] [ 161.397957] [<c0366fe8>] ? driver_probe_device+0x17b/0x30e [ 161.397960] [<c0366fe8>] ? driver_probe_device+0x17b/0x30e [ 161.397963] [<c03656e2>] ? bus_for_each_drv+0x59/0x68 [ 161.397966] [<c03656e2>] ? bus_for_each_drv+0x59/0x68 [ 161.397969] [<c0366d96>] ? __device_attach+0x91/0x105 [ 161.397972] [<c036727c>] ? driver_allows_async_probing+0x2f/0x2f [ 161.397976] [<c036636a>] ? bus_probe_device+0x27/0x6b [ 161.397979] [<c036636a>] ? bus_probe_device+0x27/0x6b [ 161.397982] [<c0364af0>] ? device_add+0x289/0x4be [ 161.397985] [<c035f7e9>] ? add_device_randomness+0x84/0x9c [ 161.397993] [<e1e2521a>] ? usb_new_device+0x29d/0x3b5 [usbcore] [ 161.398001] [<e1e2521a>] ? usb_new_device+0x29d/0x3b5 [usbcore] [ 161.398010] [<e1e26949>] ? hub_event+0xb32/0xed8 [usbcore] [ 161.398017] [<e1e26949>] ? hub_event+0xb32/0xed8 [usbcore] [ 161.398026] [<e1e25d06>] ? usb_remote_wakeup+0x6f/0x7d [usbcore] [ 161.398031] [<c01484b7>] ? process_one_work+0x174/0x2bc [ 161.398034] [<c01484b7>] ? process_one_work+0x174/0x2bc [ 161.398037] [<c0148a93>] ? worker_thread+0x22c/0x2f6 [ 161.398040] [<c0148867>] ? rescuer_thread+0x23f/0x23f [ 161.398043] [<c014be62>] ? kthread+0xa4/0xa9 [ 161.398046] [<c04be662>] ? ret_from_kernel_thread+0xe/0x24 [ 161.398049] [<c014bdbe>] ? kthread_create_on_node+0x101/0x101 [ 161.398085] Code: 14 89 83 b4 04 00 00 8b 45 94 89 43 04 8b 45 ac 89 43 08 8b 85 7c ff ff ff 89 83 c0 04 00 00 8b 45 a8 89 03 8b 45 c0 85 c0 74 0a <0f> b6 40 03 89 83 c8 04 00 00 f6 45 9c 04 74 07 83 a3 c8 04 00 [ 161.398091] EIP: [<e086ad09>] acm_probe+0x580/0xd1e [cdc_acm] SS:ESP 0068:df4dbb80 [ 161.398092] CR2: 0000000000000249 [ 161.398096] ---[ end trace da016e6d3520a331 ]--- [ 161.398152] BUG: unable to handle kernel paging request at ffffffec [ 161.398156] IP: [<c014c304>] kthread_data+0xf/0x13 [ 161.398159] *pde = 00735067 *pte = 00000000 [ 161.398161] Oops: 0000 [#2] SMP [ 161.398197] Modules linked in: cdc_acm radeon drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm agpgart i2c_algo_bit fbcon bitblit softcursor font tileblit binfmt_misc snd_pcm_oss snd_mixer_oss usb_storage usbhid ipw2200 libipw lib80211 snd_intel8x0 cfg80211 snd_ac97_codec ac97_bus uhci_hcd snd_pcm ehci_pci snd_timer snd ehci_hcd rfkill usbcore soundcore via_rhine firmware_class ppdev pcspkr parport_pc mii lpc_ich parport fan usb_common acpi_cpufreq thermal mfd_core floppy button processor [ 161.398200] CPU: 0 PID: 4 Comm: kworker/0:0 Tainted: G D 4.8.8 #2 [ 161.398202] Hardware name: MEDIONPC MS-7048/MS-7048, BIOS 6.00 PG 02/12/2004 [ 161.398217] task: df4c9500 task.stack: df4da000 [ 161.398219] EIP: 0060:[<c014c304>] EFLAGS: 00010002 CPU: 0 [ 161.398221] EIP is at kthread_data+0xf/0x13 [ 161.398223] EAX: 00000000 EBX: df4dc000 ECX: dec92374 EDX: df4c9500 [ 161.398225] ESI: df4c97b4 EDI: dfbd0960 EBP: df4dbf48 ESP: df4dbf44 [ 161.398227] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 [ 161.398229] CR0: 80050033 CR2: 00000014 CR3: 1c45f000 CR4: 00000690 [ 161.398231] Stack: [ 161.398237] c0148bbb df4dbf6c c04bb2a4 df401d80 c01e2b00 df4c9500 00000001 df4dc000 [ 161.398244] df4dbd50 df4dbf98 df4dbf78 c04bb669 df4c9500 df4dbfac c0139827 df4c9888 [ 161.398250] 01000000 df4c972c df4c8000 00000001 00000000 df4dbf98 df4dbf98 00000009 [ 161.398251] Call Trace: [ 161.398254] [<c0148bbb>] ? wq_worker_sleeping+0xd/0x75 [ 161.398259] [<c04bb2a4>] ? __schedule+0xcc/0x424 [ 161.398263] [<c01e2b00>] ? __slab_free+0x266/0x270 [ 161.398266] [<c04bb669>] ? schedule+0x6d/0x7a [ 161.398270] [<c0139827>] ? do_exit+0x74d/0x775 [ 161.398274] [<c04bf679>] ? rewind_stack_do_exit+0x11/0x13 [ 161.398277] [<c014bdbe>] ? kthread_create_on_node+0x101/0x101 [ 161.398312] Code: 8d 44 90 4c c0 8d 0c 95 00 00 00 00 29 cb b9 02 00 00 00 89 da 5b 5d e9 f5 fd ff ff 55 89 e5 3e 8d 74 26 00 8b 80 84 02 00 00 5d <8b> 40 ec c3 55 89 e5 52 3e 8d 74 26 00 b9 04 00 00 00 8b 90 84 [ 161.398316] EIP: [<c014c304>] kthread_data+0xf/0x13 SS:ESP 0068:df4dbf44 [ 161.398318] CR2: 00000000ffffffec [ 161.398320] ---[ end trace da016e6d3520a332 ]--- [ 161.398321] Fixing recursive fault but reboot is needed! Regards, Wim.
