Re: [syzbot] KASAN: null-ptr-deref Write in rhashtable_free_and_destroy (2)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    9f4ad9e4 Linux 5.12
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12e92c5dd00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=39164acdef826e06
dashboard link: https://syzkaller.appspot.com/bug?extid=860268315ba86ea6b96b
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13438cb9d00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10d37705d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+860268315ba86ea6b96b@xxxxxxxxxxxxxxxxxxxxxxxxx

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BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: null-ptr-deref in test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:70 [inline]
BUG: KASAN: null-ptr-deref in try_to_grab_pending.part.0+0x26/0x770 kernel/workqueue.c:1257
Write of size 8 at addr 0000000000000088 by task kworker/0:0/5

CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events cfg80211_destroy_iface_wk
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 __kasan_report mm/kasan/report.c:403 [inline]
 kasan_report.cold+0x5f/0xd8 mm/kasan/report.c:416
 check_region_inline mm/kasan/generic.c:180 [inline]
 kasan_check_range+0x13d/0x180 mm/kasan/generic.c:186
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:70 [inline]
 try_to_grab_pending.part.0+0x26/0x770 kernel/workqueue.c:1257
 try_to_grab_pending+0xa1/0xd0 kernel/workqueue.c:1310
 __cancel_work_timer+0xa6/0x570 kernel/workqueue.c:3098
 rhashtable_free_and_destroy+0x2b/0x920 lib/rhashtable.c:1137
 mesh_table_free net/mac80211/mesh_pathtbl.c:70 [inline]
 mesh_pathtbl_unregister+0x42/0xa0 net/mac80211/mesh_pathtbl.c:812
 ieee80211_teardown_sdata+0x216/0x2d0 net/mac80211/iface.c:691
 unregister_netdevice_many+0xc4c/0x1760 net/core/dev.c:10953
 unregister_netdevice_queue+0x2dd/0x3c0 net/core/dev.c:10870
 unregister_netdevice include/linux/netdevice.h:2884 [inline]
 _cfg80211_unregister_wdev+0x485/0x740 net/wireless/core.c:1127
 ieee80211_if_remove+0x1df/0x300 net/mac80211/iface.c:2020
 ieee80211_del_iface+0x12/0x20 net/mac80211/cfg.c:144
 rdev_del_virtual_intf net/wireless/rdev-ops.h:57 [inline]
 cfg80211_destroy_ifaces+0x223/0x770 net/wireless/core.c:341
 cfg80211_destroy_iface_wk+0x2c/0x40 net/wireless/core.c:354
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
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