sudo fails and Kernel bug

[hans12345]

I use powerline to connect between different floors. It works much better than wifi and never has "outages", so that is foreign to me.
In 2005-ish, I designed and helped deploy wifi to over 1200 locations. That taught me to always avoid using wifi whenever possible. It is always a security risk and should never be used without a full VPN from the client out. Never trust just the encryption built into the wifi protocols. It cannot be trusted. Every year, we learn about different problems with wifi security. Even the newest protocols have been hacked and remain unsecured today.

To the computer, there's no difference between wired and powerline ethernet. It doesn't know anything about powerline.

I haven't used a GUI to manage network connections on Linux in at least 10 yrs. For wifi, I use a TUI, for wired, I use the config files in /etc/. Only portable systems use DHCP, with reservations. All the others use static IPs controlled by each server. DHCP servers fail sometimes and I've seen what happens to large networks when that happens - servers start dropping offline as they attempt to renew the connections and get current IPs/netmasks/gateways/DNS servers. Freshly booted systems don't join the network. It isn't pretty. We all learn from our experiences.

Hi The Fu

I admire your professional approach. I am not at your level.
Of course a LAN is a LAN even if a powerline is present.
The house here is old and the wiring is a mess. I have 3 fuseboxes! I cannot track down the cause of the powerline problems.
I acknowledge the wifi security risk, Luckily I only have 2 neighbours in range and they are old folks.

As for the GUI, I try to use it for everything. I work very slowly with the terminal.

Thanks for your help

[hans12345]

All the bad stuff seems to be at 09.27. It is strange that the GUI worked for a couple of minutes.
The kern.log at the time of the crash:

Aug 22 08:41:31 Arctic kernel: [  308.830746] ath: phy0: Short RX data len, dropping (dlen: 4)
Aug 22 09:27:33 Arctic kernel: [ 3070.503979] usb 1-6: ath: firmware panic! exccause: 0x0000000d; pc: 0x0090ae81; badvaddr: 0x10ff4038.
Aug 22 09:27:33 Arctic kernel: [ 3070.626365] usb 1-6: USB disconnect, device number 2
Aug 22 09:27:33 Arctic kernel: [ 3070.642106] wlx74ea3a8f3e6d: deauthenticating from 8c:3b:ad:fc:81:66 by local choice (Reason: 3=DEAUTH_LEAVING)
Aug 22 09:27:33 Arctic kernel: [ 3070.906134] ------------[ cut here ]------------
Aug 22 09:27:33 Arctic kernel: [ 3070.906139] kernel BUG at mm/slub.c:306!
Aug 22 09:27:33 Arctic kernel: [ 3070.906154] invalid opcode: 0000 [#1] SMP PTI
Aug 22 09:27:33 Arctic kernel: [ 3070.906161] CPU: 2 PID: 262 Comm: kworker/u8:7 Not tainted 5.4.0-42-generic #46-Ubuntu
Aug 22 09:27:33 Arctic kernel: [ 3070.906164] Hardware name: System manufacturer System Product Name/PRIME B250M-A, BIOS 0614 04/18/2017
Aug 22 09:27:33 Arctic kernel: [ 3070.906180] Workqueue: phy0 ath9k_htc_ani_work [ath9k_htc]
Aug 22 09:27:33 Arctic kernel: [ 3070.906190] RIP: 0010:__slab_free+0x189/0x330
Aug 22 09:27:33 Arctic kernel: [ 3070.906195] Code: 00 48 89 c7 fa 66 0f 1f 44 00 00 f0 49 0f ba 2c 24 00 72 65 4d 3b 6c 24 20 74 11 49 0f ba 34 24 00 57 9d 0f 1f 44 00 00 eb 9f <0f> 0b 49 3b 5c 24 28 75 e8 48 8b 44 24 28 49 89 4c 24 28 49 89 44
Aug 22 09:27:33 Arctic kernel: [ 3070.906199] RSP: 0018:ffffb101c050bba0 EFLAGS: 00010246
Aug 22 09:27:33 Arctic kernel: [ 3070.906204] RAX: ffff931b230db800 RBX: 000000008010000b RCX: ffff931b230db800
Aug 22 09:27:33 Arctic kernel: [ 3070.906207] RDX: ffff931b230db800 RSI: ffffe597908c3680 RDI: ffff931b24c02e00
Aug 22 09:27:33 Arctic kernel: [ 3070.906210] RBP: ffffb101c050bc40 R08: 0000000000000001 R09: ffffffffba518c35
Aug 22 09:27:33 Arctic kernel: [ 3070.906213] R10: ffff931b230db800 R11: 0000000000000001 R12: ffffe597908c3680
Aug 22 09:27:33 Arctic kernel: [ 3070.906216] R13: ffff931b230db800 R14: ffff931b24c02e00 R15: ffffb101c050bd48
Aug 22 09:27:33 Arctic kernel: [ 3070.906221] FS:  0000000000000000(0000) GS:ffff931b26b00000(0000) knlGS:0000000000000000
Aug 22 09:27:33 Arctic kernel: [ 3070.906224] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Aug 22 09:27:33 Arctic kernel: [ 3070.906227] CR2: 00007fa5530df000 CR3: 000000024500a002 CR4: 00000000003606e0
Aug 22 09:27:33 Arctic kernel: [ 3070.906230] Call Trace:
Aug 22 09:27:33 Arctic kernel: [ 3070.906243]  ? del_timer_sync+0x29/0x40
Aug 22 09:27:33 Arctic kernel: [ 3070.906250]  ? schedule_timeout+0x15a/0x2f0
Aug 22 09:27:33 Arctic kernel: [ 3070.906257]  ? skb_free_head+0x25/0x30
Aug 22 09:27:33 Arctic kernel: [ 3070.906261]  kfree+0x231/0x250
Aug 22 09:27:33 Arctic kernel: [ 3070.906266]  skb_free_head+0x25/0x30
Aug 22 09:27:33 Arctic kernel: [ 3070.906272]  skb_release_data+0x11d/0x180
Aug 22 09:27:33 Arctic kernel: [ 3070.906282]  ? ath9k_wmi_cmd+0x1a5/0x1c0 [ath9k_htc]
Aug 22 09:27:33 Arctic kernel: [ 3070.906287]  skb_release_all+0x26/0x30
Aug 22 09:27:33 Arctic kernel: [ 3070.906293]  kfree_skb+0x32/0xa0
Aug 22 09:27:33 Arctic kernel: [ 3070.906301]  ath9k_wmi_cmd+0x1a5/0x1c0 [ath9k_htc]
Aug 22 09:27:33 Arctic kernel: [ 3070.906311]  ath9k_regread+0x48/0x70 [ath9k_htc]
Aug 22 09:27:33 Arctic kernel: [ 3070.906332]  ar9285_hw_pa_cal+0x317/0x520 [ath9k_hw]
Aug 22 09:27:33 Arctic kernel: [ 3070.906348]  ar9002_hw_pa_cal+0x36/0x60 [ath9k_hw]
Aug 22 09:27:33 Arctic kernel: [ 3070.906362]  ar9002_hw_calibrate+0x102/0x440 [ath9k_hw]
Aug 22 09:27:33 Arctic kernel: [ 3070.906372]  ath9k_htc_ani_work+0x118/0x1a0 [ath9k_htc]
Aug 22 09:27:33 Arctic kernel: [ 3070.906379]  process_one_work+0x1eb/0x3b0
Aug 22 09:27:33 Arctic kernel: [ 3070.906385]  worker_thread+0x4d/0x400
Aug 22 09:27:33 Arctic kernel: [ 3070.906391]  kthread+0x104/0x140
Aug 22 09:27:33 Arctic kernel: [ 3070.906397]  ? process_one_work+0x3b0/0x3b0
Aug 22 09:27:33 Arctic kernel: [ 3070.906401]  ? kthread_park+0x90/0x90
Aug 22 09:27:33 Arctic kernel: [ 3070.906408]  ret_from_fork+0x35/0x40
Aug 22 09:27:33 Arctic kernel: [ 3070.906413] Modules linked in: ccm intel_rapl_msr mei_hdcp intel_rapl_common x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_codec_hdmi snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core snd_hwdep ath9k_htc snd_pcm ath9k_common crct10dif_pclmul ghash_clmulni_intel ath9k_hw snd_seq_midi snd_seq_midi_event snd_rawmidi ath aesni_intel amdgpu crypto_simd mac80211 cryptd glue_helper intel_cstate snd_seq intel_rapl_perf amd_iommu_v2 snd_seq_device gpu_sched snd_timer cfg80211 ttm eeepc_wmi asus_wmi input_leds drm_kms_helper sparse_keymap wmi_bmof snd mxm_wmi libarc4 i2c_algo_bit serio_raw fb_sys_fops syscopyarea mei_me sysfillrect soundcore sysimgblt mei acpi_pad mac_hid sch_fq_codel parport_pc ppdev lp parport drm ip_tables x_tables autofs4 nvme ahci r8169 crc32_pclmul psmouse nvme_core i2c_i801 realtek libahci wmi video
Aug 22 09:27:33 Arctic kernel: [ 3070.906482] ---[ end trace db8c2e15eab6e90f ]---
Aug 22 09:27:33 Arctic kernel: [ 3070.906487] RIP: 0010:__slab_free+0x189/0x330
Aug 22 09:27:33 Arctic kernel: [ 3070.906492] Code: 00 48 89 c7 fa 66 0f 1f 44 00 00 f0 49 0f ba 2c 24 00 72 65 4d 3b 6c 24 20 74 11 49 0f ba 34 24 00 57 9d 0f 1f 44 00 00 eb 9f <0f> 0b 49 3b 5c 24 28 75 e8 48 8b 44 24 28 49 89 4c 24 28 49 89 44
Aug 22 09:27:33 Arctic kernel: [ 3070.906495] RSP: 0018:ffffb101c050bba0 EFLAGS: 00010246
Aug 22 09:27:33 Arctic kernel: [ 3070.906499] RAX: ffff931b230db800 RBX: 000000008010000b RCX: ffff931b230db800
Aug 22 09:27:33 Arctic kernel: [ 3070.906502] RDX: ffff931b230db800 RSI: ffffe597908c3680 RDI: ffff931b24c02e00
Aug 22 09:27:33 Arctic kernel: [ 3070.906505] RBP: ffffb101c050bc40 R08: 0000000000000001 R09: ffffffffba518c35
Aug 22 09:27:33 Arctic kernel: [ 3070.906508] R10: ffff931b230db800 R11: 0000000000000001 R12: ffffe597908c3680
Aug 22 09:27:33 Arctic kernel: [ 3070.906511] R13: ffff931b230db800 R14: ffff931b24c02e00 R15: ffffb101c050bd48
Aug 22 09:27:33 Arctic kernel: [ 3070.906515] FS:  0000000000000000(0000) GS:ffff931b26b00000(0000) knlGS:0000000000000000
Aug 22 09:27:33 Arctic kernel: [ 3070.906518] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Aug 22 09:27:33 Arctic kernel: [ 3070.906521] CR2: 00007fa5530df000 CR3: 000000024500a002 CR4: 00000000003606e0
Aug 22 09:33:27 Arctic kernel: [    0.000000] microcode: microcode updated early to revision 0xd6, date = 2020-04-23

[TheFu]

Seems clear. The problem is with a USB device using the ath9k driver.

           Device-2: Qualcomm Atheros TP-Link TL-WN821N v3 / TL-WN822N v2 802.11n [Atheros AR7010+AR9287] type: USB 
           driver: ath9k_htc bus ID: 1-6:2 chip ID: 0cf3:7015 serial: <filter> 
           IF: wlx74ea3a8f3e6d state: up mac: <filter>

That is one of the problems. We don't know if it is the only problem.

[Doug S]

Did you ever try the mainline kernel? Your issue sure sounds like that bug report I referred you to earlier.

[TheFu]

Did you ever try the mainline kernel? Your issue sure sounds like that bug report I referred you to earlier.

Sure does.

For the record, the patch was merged to v5.4.47 (and other newer kernels)

5.4.0-42-generic is the current 20.04 default kernel, so going out of the way to get a newer one will be needed to use that wifi usb device.

[hans12345]

Did you ever try the mainline kernel? Your issue sure sounds like that bug report I referred you to earlier.

Thanks Doug S

I noted your proposal but for me it looks a bit heavy so I was exploring other options first.

See my next post for these steps.

[hans12345]

Seems clear. The problem is which a USB device using the ath9k driver.

           Device-2: Qualcomm Atheros TP-Link TL-WN821N v3 / TL-WN822N v2 802.11n [Atheros AR7010+AR9287] type: USB 
           driver: ath9k_htc bus ID: 1-6:2 chip ID: 0cf3:7015 serial: <filter> 
           IF: wlx74ea3a8f3e6d state: up mac: <filter>

That is one of the problems. We don't know if it is the only problem.

Thanks TheFu

OK, let me take these steps:

- switch back to the LAN (powerline) connection
- upgrade to the 20.04.1 point release (for some reason I missed the release announcement)

Edit: Whoops - it seems that I have the point release already !

[Doug S]

I noted your proposal but for me it looks a bit heavy so I was exploring other options first.

It is actually pretty trivial to try, but O.K. Watch for kernel 5.4.0-44.48 (= mainline 5.4.55), which has been in proposed since August 10th, and so should be out soon. It will have the fix.

[hans12345]

24 hours and no crash.

Can my problems be caused by a rogue wifi USB stick?

For the record it is a TP-Link TL-WN821N

[hans12345]

Hi Doug S
This is what I have:
cat /proc/version_signature
Ubuntu 5.4.0-42.46-generic 5.4.44
and this is what you suggest?
linux-generic-hwe-20.04_5.4.0.44.48_amd64.deb 5.4.0.44.48 amd64 Ubuntu Proposed Main Official