Chromebox: Guado running 9765.21.0 (Official Build) dev-channel guado test

What steps will reproduce the problem?
(1)start meeting
(2)start loop:
(2.1)cutting power for one usb port
(2.2) wait for 1 second
(2.3) restoring power for usb port
(2.4) wait for 15 seconds
(2.5) repeat 2-5 for other 2 usb ports. 
(2.6) wait for 30 seconds


What is the expected result?
After power is restored all usb devices connected to Guado should be enumerated.

What happens instead?
After finishing 26 loops, kernel crash. Guado reboots.

Please use labels and text to provide additional information.
============
localhost ~ # tail /var/log/eventlog.txt 
205 | 2017-08-23 15:19:36 | System boot | 973
206 | 2017-08-23 15:19:36 | System Reset
207 | 2017-08-23 15:19:36 | Wake Source | GPIO | 27
208 | 2017-08-23 15:19:36 | Chrome OS Developer Mode
209 | 2017-08-23 16:12:38 | Kernel Event | Oops   <<<<<<<<<<<<
210 | 2017-08-23 16:12:38 | Kernel Event | Panic <<<<<<<<<<<<
211 | 2017-08-23 16:12:39 | System boot | 974
212 | 2017-08-23 16:12:39 | System Reset
213 | 2017-08-23 16:12:39 | Wake Source | GPIO | 27
214 | 2017-08-23 16:12:39 | Chrome OS Developer Mode

6>[ 3153.022029] usb 2-2: USB disconnect, device number 30
<1>[ 3153.029310] BUG: unable to handle kernel NULL pointer dereference at           (null)
<1>[ 3153.029344] IP: [<ffffffffa1ffd82f>] usb_ifnum_to_if+0x2c/0x3f
<5>[ 3153.029374] PGD 0
<5>[ 3153.029387] Oops: 0000 [#1] PREEMPT SMP
<0>[ 3153.031878] gsmi: Log Shutdown Reason 0x03
<5>[ 3153.031893] Modules linked in: rfcomm evdi uinput i2c_dev memc_x86 cmac x86_pkg_temp_thermal snd_hda_codec_realtek snd_hda_codec_hdmi snd_hda_codec_generic snd_soc_sst_acpi zram snd_hda_intel snd_hda_controller snd_hda_codec fuse joydev hid_multitouch snd_usb_audio snd_usbmidi_lib snd_hwdep uvcvideo videobuf2_vmalloc ip6table_filter ip6_tables snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device btusb btbcm btintel bluetooth iwlmvm r8169 mii iwlwifi iwl7000_mac80211 cfg80211
<5>[ 3153.032104] CPU: 3 PID: 24545 Comm: V4L2CaptureThre Not tainted 3.14.0 #1
<5>[ 3153.032123] Hardware name: GOOGLE Guado, BIOS Google_Guado.6301.108.4 04/01/2015
<5>[ 3153.032144] task: ffff88014210d220 ti: ffff880059768000 task.ti: ffff880059768000
<5>[ 3153.032163] RIP: 0010:[<ffffffffa1ffd82f>]  [<ffffffffa1ffd82f>] usb_ifnum_to_if+0x2c/0x3f
<5>[ 3153.032192] RSP: 0018:ffff880059769df8  EFLAGS: 00010202
<5>[ 3153.032207] RAX: 0000000000000000 RBX: ffff8800596f7800 RCX: ffff88017814b000
<5>[ 3153.032224] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000004
<5>[ 3153.032243] RBP: ffff880059769df8 R08: 0000000000000008 R09: 0000000000000003
<5>[ 3153.032261] R10: ffffffffa28c8cd8 R11: 0000000000000001 R12: ffff880064510800
<5>[ 3153.032280] R13: 00000000ffffff8f R14: ffff88005ddc1288 R15: ffff880178021000
<5>[ 3153.032301] FS:  0000718aaff0a700(0000) GS:ffff88017ed80000(0000) knlGS:0000000000000000
<5>[ 3153.032321] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<5>[ 3153.032339] CR2: 0000000000000000 CR3: 0000000174b0f000 CR4: 00000000003407e0
<5>[ 3153.032356] Stack:
<5>[ 3153.032365]  ffff880059769e38 ffffffffa200888c 0000000000000001 ffff880064510800
<5>[ 3153.032395]  ffff880064510800 ffff8801422bb040 ffff88005ddc1288 ffff8801422bb050
<5>[ 3153.032424]  ffff880059769e60 ffffffffc021b845 ffff880164354f00 ffff880064510800
<5>[ 3153.032454] Call Trace:
<5>[ 3153.032475]  [<ffffffffa200888c>] usb_set_interface+0x35/0x286
<5>[ 3153.032505]  [<ffffffffc021b845>] uvc_video_enable+0x2e/0x115e [uvcvideo]
<5>[ 3153.032534]  [<ffffffffc021970f>] uvc_queue_next_buffer+0x1bc0/0x33e6 [uvcvideo]
<5>[ 3153.032559]  [<ffffffffa206d911>] v4l2_release+0x30/0x6a
<5>[ 3153.032579]  [<ffffffffa1d49469>] __fput+0xdd/0x1c6
<5>[ 3153.032599]  [<ffffffffa1d49588>] ____fput+0xe/0x10
<5>[ 3153.032619]  [<ffffffffa1c78a29>] task_work_run+0x7d/0x93
<5>[ 3153.032639]  [<ffffffffa1c023da>] do_notify_resume+0x57/0x5b
<5>[ 3153.032660]  [<ffffffffa2223e6e>] int_signal+0x12/0x17
<5>[ 3153.032675] Code: 1f 44 00 00 55 48 8b 8f a0 03 00 00 31 c0 48 89 e5 48 85 c9 74 26 0f b6 79 04 31 d2 39 d7 7e 1a 48 8b 84 d1 98 00 00 00 48 ff c2 <4c> 8b 00 45 0f b6 40 02 41 39 f0 75 e4 eb 02 31 c0 5d c3 0f 1f
<1>[ 3153.032890] RIP  [<ffffffffa1ffd82f>] usb_ifnum_to_if+0x2c/0x3f
<5>[ 3153.032915]  RSP <ffff880059769df8>
<5>[ 3153.032926] CR2: 0000000000000000
<4>[ 3153.032940] ---[ end trace 231fa3cef628829b ]---
<0>[ 3153.042998] Kernel panic - not syncing: Fatal exception
<0>[ 3153.043026] Kernel Offset: 0x20c00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
<0>[ 3153.043141] gsmi: Log Shutdown Reason 0x02