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BUG: KASAN: null-ptr-deref in memset include/linux/string.h:366 [inline]
BUG: KASAN: null-ptr-deref in choke_reset+0x208/0x340 net/sched/sch_choke.c:326
Write of size 8 at addr 0000000000000000 by task kworker/u4:1/21

CPU: 1 PID: 21 Comm: kworker/u4:1 Not tainted 5.7.0-rc1-next-20200415-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+0x188/0x20d lib/dump_stack.c:118
 __kasan_report.cold+0x5/0x4d mm/kasan/report.c:515
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 check_memory_region_inline mm/kasan/generic.c:187 [inline]
 check_memory_region+0x141/0x190 mm/kasan/generic.c:193
 memset+0x20/0x40 mm/kasan/common.c:85
 memset include/linux/string.h:366 [inline]
 choke_reset+0x208/0x340 net/sched/sch_choke.c:326
 qdisc_destroy+0xe0/0x690 net/sched/sch_generic.c:956
 qdisc_put+0xcd/0xe0 net/sched/sch_generic.c:985
 dev_shutdown+0x2b5/0x492 net/sched/sch_generic.c:1311
 rollback_registered_many+0x603/0xe70 net/core/dev.c:8821
 unregister_netdevice_many.part.0+0x16/0x1e0 net/core/dev.c:9988
 unregister_netdevice_many net/core/dev.c:9987 [inline]
 default_device_exit_batch+0x311/0x3d0 net/core/dev.c:10471
 ops_exit_list.isra.0+0x103/0x150 net/core/net_namespace.c:189
 cleanup_net+0x511/0xa50 net/core/net_namespace.c:603
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
 worker_thread+0x96/0xe20 kernel/workqueue.c:2414
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
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