mac80211_hwsim: wmediumd released netlink socket, switching to perfect channel medium
------------[ cut here ]------------
Have pending ack frames!
WARNING: CPU: 1 PID: 12215 at net/mac80211/main.c:1265 ieee80211_free_ack_frame+0x48/0x50 net/mac80211/main.c:1265
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 12215 Comm: kworker/u4:0 Not tainted 4.19.155-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2fe lib/dump_stack.c:118
 panic+0x26a/0x50e kernel/panic.c:186
 __warn.cold+0x20/0x61 kernel/panic.c:541
 report_bug+0x262/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 fixup_bug arch/x86/kernel/traps.c:173 [inline]
 do_error_trap+0x1d7/0x310 arch/x86/kernel/traps.c:296
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:ieee80211_free_ack_frame+0x48/0x50 net/mac80211/main.c:1265
Code: e8 dd 98 b0 f9 48 89 ef e8 b5 7e d9 fe 31 c0 5b 5d c3 e8 cb 98 b0 f9 48 c7 c7 20 83 66 89 c6 05 72 5b 5a 03 01 e8 03 77 84 f9 <0f> 0b eb d2 0f 1f 40 00 41 57 41 56 41 55 41 54 49 bc 00 00 00 00
RSP: 0018:ffff8880938ffa28 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff814fda81 RDI: ffffed101271ff37
RBP: ffff8880b4ffa280 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: ffff888093d792d8
R13: dffffc0000000000 R14: ffffffff87b43590 R15: 0000000000000000
 idr_for_each+0x132/0x290 lib/idr.c:211
 ieee80211_free_hw+0x88/0x140 net/mac80211/main.c:1280
 mac80211_hwsim_del_radio drivers/net/wireless/mac80211_hwsim.c:2998 [inline]
 hwsim_exit_net+0xbdf/0x1580 drivers/net/wireless/mac80211_hwsim.c:3666
 ops_exit_list+0xa5/0x150 net/core/net_namespace.c:153
 cleanup_net+0x3b4/0x8b0 net/core/net_namespace.c:553
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Kernel Offset: disabled
Rebooting in 86400 seconds..