Description of problem:
While doing sudo dnf update right after boot up in Fedora 28 Workstation, the connection lost at about 80% while trying to retrieve updates to firefox and chrome browsers.
Message dnf: downloaded packages are in cache, (run dnf with clear to remove cached files or so)
Retried sudo dnf update and it froze.
Brought up another terminal and executed sudo reboot ... nothing
Brought up another terminal and executed init 0 screen went black (gui shutdown?
pressed ctrl+alt+F! to see progress... several jobs were being waited on... 30 s, 1 min,  1:30 min,... no kill..
pressed ctrl+alt+del nothing
pressed repeatedly ctrl+alt+del and eventually a message showed up "pressed ctrl+alt+del 7 times less than 2 seconds" killing jobs.
it killed about 10 jobs but it got stuck again.
pressed f1, fedora boot/shutdown was present, pressed f1 again (toggle) could switch between CLI and shutdown screen.
machine froze...
Pressed power off.  boot up and report this.

Additional info:
reporter:       libreport-2.9.5
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
PGD 0 P4D 0 
Oops: 0000 [#1] SMP PTI
Modules linked in: fuse xt_CHECKSUM ipt_MASQUERADE nf_nat_masquerade_ipv4 tun devlink nf_conntrack_netbios_ns nf_conntrack_broadcast xt_CT ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set nfnetlink ebtable_nat ebtable_broute bridge stp llc ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_raw ip6table_security iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack libcrc32c iptable_mangle iptable_raw iptable_security ebtable_filter ebtables ip6table_filter ip6_tables sunrpc intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm brcmfmac snd_hda_codec_realtek irqbypass crct10dif_pclmul brcmutil snd_hda_codec_generic crc32_pclmul mmc_core snd_hda_codec_hdmi ghash_clmulni_intel snd_hda_intel intel_cstate
 iTCO_wdt gpio_ich intel_uncore iTCO_vendor_support snd_hda_codec intel_rapl_perf cfg80211 snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm rfkill i2c_i801 snd_timer mei_me snd lpc_ich soundcore mei pcc_cpufreq shpchp radeon i2c_algo_bit drm_kms_helper ttm drm crc32c_intel serio_raw
CPU: 6 PID: 219 Comm: kworker/6:3 Not tainted 4.17.19-200.fc28.x86_64 #1
Hardware name:  /DH67GD, BIOS BLH6710H.86A.0162.2018.0412.1542 04/12/2018
Workqueue: events reg_regdb_apply [cfg80211]
RIP: 0010:brcmf_fil_iovar_data_get+0x1b/0xb0 [brcmfmac]
RSP: 0018:ffffabdb41d3bdd8 EFLAGS: 00010293
RAX: 0000000000000017 RBX: ffff9bf5ed7a9ec0 RCX: 000000000000000c
RDX: ffffabdb41d3be14 RSI: ffffffffc073916d RDI: 0000000000000000
RBP: ffff9bf6526a6800 R08: ffff9bf653c5c2e0 R09: 0000000000000994
R10: ffff9bf64fe09380 R11: 0000000000000000 R12: 000000000000000c
R13: ffffabdb41d3be14 R14: ffffffffc073916d R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff9bf65f580000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001d220a004 CR4: 00000000000606e0
Call Trace:
 brcmf_cfg80211_reg_notifier+0x86/0x210 [brcmfmac]
 set_regdom+0x12d/0x5a0 [cfg80211]
 reg_regdb_apply+0x76/0xb0 [cfg80211]
 process_one_work+0x187/0x340
 worker_thread+0x2e/0x380
 ? pwq_unbound_release_workfn+0xd0/0xd0
 kthread+0x112/0x130
 ? kthread_create_worker_on_cpu+0x70/0x70
 ret_from_fork+0x35/0x40
Code: d0 3e 73 c0 e8 e0 98 01 00 eb c8 0f 1f 44 00 00 66 66 66 66 90 41 57 49 89 ff 41 56 49 89 f6 41 55 49 89 d5 41 54 41 89 cc 55 53 <48> 8b 1f 48 8d ab 70 01 00 00 48 81 c3 90 01 00 00 48 89 ef e8 
RIP: brcmf_fil_iovar_data_get+0x1b/0xb0 [brcmfmac] RSP: ffffabdb41d3bdd8
CR2: 0000000000000000