Kernel bug: possible deadlock in ieee80211_remove_interfaces
Subsystem: wireless
Status: fixed

Crash report:
======================================================
WARNING: possible circular locking dependency detected
6.13.0-syzkaller-09585-gb4b0881156fb #0 Not tainted
------------------------------------------------------
kworker/u4:10/1090 is trying to acquire lock:
ffffffff8fcbef88 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_acquire_if_cleanup_net net/core/dev.c:10272 [inline]
ffffffff8fcbef88 (rtnl_mutex){+.+.}-{4:4}, at: unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11792

but task is already holding lock:
ffff888044098768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6061 [inline]
ffff888044098768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_remove_interfaces+0x129/0x700 net/mac80211/iface.c:2280

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&rdev->wiphy.mtx){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
       wiphy_lock include/net/cfg80211.h:6046 [inline]
       wiphy_register+0x1a49/0x27b0 net/wireless/core.c:1003
       ieee80211_register_hw+0x354e/0x4240 net/mac80211/main.c:1587
       mac80211_hwsim_new_radio+0x2a9f/0x4aa0 drivers/net/wireless/virtual/mac80211_hwsim.c:5558
       init_mac80211_hwsim+0x87a/0xb00 drivers/net/wireless/virtual/mac80211_hwsim.c:6910
       do_one_initcall+0x248/0x870 init/main.c:1257
       do_initcall_level+0x157/0x210 init/main.c:1319
       do_initcalls+0x3f/0x80 init/main.c:1335
       kernel_init_freeable+0x435/0x5d0 init/main.c:1568
       kernel_init+0x1d/0x2b0 init/main.c:1457
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (rtnl_mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
       rtnl_acquire_if_cleanup_net net/core/dev.c:10272 [inline]
       unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11792
       unregister_netdevice_many net/core/dev.c:11875 [inline]
       unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11741
       unregister_netdevice include/linux/netdevice.h:3329 [inline]
       _cfg80211_unregister_wdev+0x163/0x590 net/wireless/core.c:1248
       ieee80211_remove_interfaces+0x4ef/0x700 net/mac80211/iface.c:2305
       ieee80211_unregister_hw+0x5d/0x2c0 net/mac80211/main.c:1681
       mac80211_hwsim_del_radio+0x2c4/0x4c0 drivers/net/wireless/virtual/mac80211_hwsim.c:5664
       hwsim_exit_net+0x5c1/0x670 drivers/net/wireless/virtual/mac80211_hwsim.c:6544
       ops_exit_list net/core/net_namespace.c:172 [inline]
       cleanup_net+0x812/0xd60 net/core/net_namespace.c:652
       process_one_work kernel/workqueue.c:3236 [inline]
       process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
       worker_thread+0x870/0xd30 kernel/workqueue.c:3398
       kthread+0x7a9/0x920 kernel/kthread.c:464
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rdev->wiphy.mtx);
                               lock(rtnl_mutex);
                               lock(&rdev->wiphy.mtx);
  lock(rtnl_mutex);

 *** DEADLOCK ***

4 locks held by kworker/u4:10/1090:
 #0: ffff88801baef148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
 #0: ffff88801baef148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: ffffc9000255fc60 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 #1: ffffc9000255fc60 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: ffffffff8fcb29d0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0x17a/0xd60 net/core/net_namespace.c:606
 #3: ffff888044098768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6061 [inline]
 #3: ffff888044098768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_remove_interfaces+0x129/0x700 net/mac80211/iface.c:2280

stack backtrace:
CPU: 0 UID: 0 PID: 1090 Comm: kworker/u4:10 Not tainted 6.13.0-syzkaller-09585-gb4b0881156fb #0
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
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2076
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208
 check_prev_add kernel/locking/lockdep.c:3163 [inline]
 check_prevs_add kernel/locking/lockdep.c:3282 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
 rtnl_acquire_if_cleanup_net net/core/dev.c:10272 [inline]
 unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11792
 unregister_netdevice_many net/core/dev.c:11875 [inline]
 unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11741
 unregister_netdevice include/linux/netdevice.h:3329 [inline]
 _cfg80211_unregister_wdev+0x163/0x590 net/wireless/core.c:1248
 ieee80211_remove_interfaces+0x4ef/0x700 net/mac80211/iface.c:2305
 ieee80211_unregister_hw+0x5d/0x2c0 net/mac80211/main.c:1681
 mac80211_hwsim_del_radio+0x2c4/0x4c0 drivers/net/wireless/virtual/mac80211_hwsim.c:5664
 hwsim_exit_net+0x5c1/0x670 drivers/net/wireless/virtual/mac80211_hwsim.c:6544
 ops_exit_list net/core/net_namespace.c:172 [inline]
 cleanup_net+0x812/0xd60 net/core/net_namespace.c:652
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>