------------[ cut here ]------------
Have pending ack frames!
WARNING: CPU: 1 PID: 8544 at net/mac80211/main.c:1701 ieee80211_free_ack_frame+0x5a/0x60 net/mac80211/main.c:1701
Modules linked in:
CPU: 1 UID: 0 PID: 8544 Comm: kworker/u32:4 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: netns cleanup_net
RIP: 0010:ieee80211_free_ack_frame+0x5a/0x60 net/mac80211/main.c:1701
Code: 31 ff e8 99 e3 68 fe 31 c0 5b 5d e9 40 b5 97 00 e8 4b ec bd f6 c6 05 3f fb 96 05 01 90 48 c7 c7 00 8f 08 8d e8 27 e6 7c f6 90 <0f> 0b 90 90 eb c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000e7e78d0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff888059d18000 RCX: ffffffff817a02f8
RDX: ffff88804d5ca440 RSI: ffffffff817a0305 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffffff8afd1ae0 R14: 0000000080000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880975b9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002f106ff8 CR3: 00000000638b4000 CR4: 0000000000352ef0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000083
DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 idr_for_each+0x143/0x270 lib/idr.c:208
 ieee80211_free_hw+0x59/0x1d0 net/mac80211/main.c:1713
 mac80211_hwsim_del_radio drivers/net/wireless/virtual/mac80211_hwsim.c:5677 [inline]
 hwsim_exit_net+0x3fd/0x7d0 drivers/net/wireless/virtual/mac80211_hwsim.c:6554
 ops_exit_list net/core/net_namespace.c:198 [inline]
 ops_undo_list+0x2ee/0xab0 net/core/net_namespace.c:251
 cleanup_net+0x408/0x890 net/core/net_namespace.c:682
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>