------------[ cut here ]------------
Have pending ack frames!
WARNING: CPU: 1 PID: 1240 at net/mac80211/main.c:1713 ieee80211_free_ack_frame+0x5a/0x60 net/mac80211/main.c:1713
Modules linked in:
CPU: 1 UID: 0 PID: 1240 Comm: kworker/u32:11 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:1713
Code: 31 ff e8 59 c2 60 fe 31 c0 5b 5d c3 cc cc cc cc e8 2b 44 f1 f6 c6 05 7a c9 9e 05 01 90 48 c7 c7 00 8b e2 8c e8 c7 73 af 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:ffffc90006647888 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff88803be13540 RCX: ffffffff817b3ee8
RDX: ffff888029114900 RSI: ffffffff817b3ef5 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: ffffffff8acbc930 R14: 0000000080000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880d6b08000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe246f156c0 CR3: 000000003efce000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 idr_for_each+0x143/0x270 lib/idr.c:208
 ieee80211_free_hw+0x59/0x1d0 net/mac80211/main.c:1725
 mac80211_hwsim_del_radio drivers/net/wireless/virtual/mac80211_hwsim.c:5912 [inline]
 hwsim_exit_net+0x7d9/0x1590 drivers/net/wireless/virtual/mac80211_hwsim.c:6799
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x2ee/0xab0 net/core/net_namespace.c:252
 cleanup_net+0x41b/0x8b0 net/core/net_namespace.c:695
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>