Subject: Re: [syzbot] [wireless?] possible deadlock in ieee80211_remove_interfaces

From: syzbot <[email-masked]>
Date: Thu, 16 Jan 2025 19:58:23 -0800

syzbot has found a reproducer for the following issue on:

HEAD commit:    8d20dcda404d selftests: drv-net-hw: inject pp_alloc_fail e..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14ef5a18580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c30f048a4f12891
dashboard link: https://syzkaller.appspot.com/bug?extid=5b9196ecf74447172a9a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15d7a1f8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5ce07c743ced/disk-8d20dcda.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/66f2a9a35d5e/vmlinux-8d20dcda.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4c790c086a46/bzImage-8d20dcda.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc7-syzkaller-01131-g8d20dcda404d #0 Not tainted
------------------------------------------------------
kworker/u8:6/3534 is trying to acquire lock:
ffffffff8fcb4a08 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_acquire_if_cleanup_net net/core/dev.c:10281 [inline]
ffffffff8fcb4a08 (rtnl_mutex){+.+.}-{4:4}, at: unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11783

but task is already holding lock:
ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6034 [inline]
ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_remove_interfaces+0x129/0x700 net/mac80211/iface.c:2276

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:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
       wiphy_lock include/net/cfg80211.h:6019 [inline]
       wiphy_register+0x1a49/0x27b0 net/wireless/core.c:1006
       ieee80211_register_hw+0x30fb/0x3e10 net/mac80211/main.c:1582
       mac80211_hwsim_new_radio+0x2a9f/0x4a90 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:1266
       do_initcall_level+0x157/0x210 init/main.c:1328
       do_initcalls+0x3f/0x80 init/main.c:1344
       kernel_init_freeable+0x435/0x5d0 init/main.c:1577
       kernel_init+0x1d/0x2b0 init/main.c:1466
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
       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:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
       rtnl_acquire_if_cleanup_net net/core/dev.c:10281 [inline]
       unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11783
       unregister_netdevice_many net/core/dev.c:11866 [inline]
       unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11732
       unregister_netdevice include/linux/netdevice.h:3320 [inline]
       _cfg80211_unregister_wdev+0x163/0x590 net/wireless/core.c:1251
       ieee80211_remove_interfaces+0x4ef/0x700 net/mac80211/iface.c:2301
       ieee80211_unregister_hw+0x5d/0x2c0 net/mac80211/main.c:1676
       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+0x2f0/0x390 kernel/kthread.c:389
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
       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/u8:6/3534:
 #0: ffff88801baf5948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
 #0: ffff88801baf5948 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
 #1: ffffc9000d507d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 #1: ffffc9000d507d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
 #2: ffffffff8fca8290 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0x17a/0xd60 net/core/net_namespace.c:606
 #3: ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6034 [inline]
 #3: ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_remove_interfaces+0x129/0x700 net/mac80211/iface.c:2276

stack backtrace:
CPU: 1 UID: 0 PID: 3534 Comm: kworker/u8:6 Not tainted 6.13.0-rc7-syzkaller-01131-g8d20dcda404d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
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:2074
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
 rtnl_acquire_if_cleanup_net net/core/dev.c:10281 [inline]
 unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11783
 unregister_netdevice_many net/core/dev.c:11866 [inline]
 unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11732
 unregister_netdevice include/linux/netdevice.h:3320 [inline]
 _cfg80211_unregister_wdev+0x163/0x590 net/wireless/core.c:1251
 ieee80211_remove_interfaces+0x4ef/0x700 net/mac80211/iface.c:2301
 ieee80211_unregister_hw+0x5d/0x2c0 net/mac80211/main.c:1676
 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+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
hsr_slave_0: left promiscuous mode
hsr_slave_1: left promiscuous mode
batman_adv: batadv0: Interface deactivated: batadv_slave_0
batman_adv: batadv0: Removing interface: batadv_slave_0
batman_adv: batadv0: Interface deactivated: batadv_slave_1
batman_adv: batadv0: Removing interface: batadv_slave_1
veth1_macvtap: left promiscuous mode
veth0_macvtap: left promiscuous mode
veth1_vlan: left promiscuous mode
veth0_vlan: left promiscuous mode
team0 (unregistering): Port device team_slave_1 removed
team0 (unregistering): Port device team_slave_0 removed
bridge0: port 2(bridge_slave_1) entered blocking state
bridge0: port 2(bridge_slave_1) entered forwarding state
bridge0: port 1(bridge_slave_0) entered blocking state
bridge0: port 1(bridge_slave_0) entered forwarding state
bridge0: port 2(bridge_slave_1) entered blocking state
bridge0: port 2(bridge_slave_1) entered forwarding state

---
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#syz test: git://repo/address.git branch-or-commit-hash
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