syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.179-syzkaller #0 Not tainted
------------------------------------------------------
udevd/3544 is trying to acquire lock:
ffff8880b8f27e78 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3199 [inline]
ffff8880b8f27e78 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline]
ffff8880b8f27e78 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x1b5/0x8a0 kernel/rcu/tree.c:3597

but task is already holding lock:
ffff888020c965b8 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&trie->lock){..-.}-{2:2}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
       trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467
       bpf_prog_1db1603a7cfa36fb+0x3d/0xaf0
       bpf_dispatcher_nop_func include/linux/bpf.h:790 [inline]
       __bpf_prog_run include/linux/filter.h:628 [inline]
       bpf_prog_run include/linux/filter.h:635 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline]
       bpf_trace_run3+0x1d1/0x380 kernel/trace/bpf_trace.c:1916
       trace_timer_start include/trace/events/timer.h:52 [inline]
       enqueue_timer+0x3ae/0x540 kernel/time/timer.c:586
       internal_add_timer kernel/time/timer.c:611 [inline]
       __mod_timer+0xa60/0xeb0 kernel/time/timer.c:1062
       dsp_cmx_send+0x21bb/0x2240 drivers/isdn/mISDN/dsp_cmx.c:1850
       call_timer_fn+0x16d/0x560 kernel/time/timer.c:1451
       expire_timers kernel/time/timer.c:1496 [inline]
       __run_timers+0x67c/0x890 kernel/time/timer.c:1767
       run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
       handle_softirqs+0x3a7/0x930 kernel/softirq.c:558
       __do_softirq kernel/softirq.c:592 [inline]
       invoke_softirq kernel/softirq.c:432 [inline]
       __irq_exit_rcu+0x157/0x240 kernel/softirq.c:641
       irq_exit_rcu+0x5/0x20 kernel/softirq.c:653
       instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
       sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
       asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
       _raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194
       __debug_check_no_obj_freed lib/debugobjects.c:982 [inline]
       debug_check_no_obj_freed+0x455/0x4e0 lib/debugobjects.c:1003
       slab_free_hook mm/slub.c:1680 [inline]
       slab_free_freelist_hook+0x86/0x160 mm/slub.c:1731
       slab_free mm/slub.c:3499 [inline]
       kfree+0xf1/0x270 mm/slub.c:4559
       tomoyo_check_open_permission+0x373/0x490 security/tomoyo/file.c:786
       security_file_open+0x5f/0xa0 security/security.c:1668
       do_dentry_open+0x315/0xfb0 fs/open.c:813
       do_open fs/namei.c:3608 [inline]
       path_openat+0x2705/0x2f20 fs/namei.c:3742
       do_filp_open+0x21c/0x460 fs/namei.c:3769
       do_sys_openat2+0x13b/0x4f0 fs/open.c:1253
       do_sys_open fs/open.c:1269 [inline]
       __do_sys_openat fs/open.c:1285 [inline]
       __se_sys_openat fs/open.c:1280 [inline]
       __x64_sys_openat+0x243/0x290 fs/open.c:1280
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&base->lock){-.-.}-{2:2}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
       lock_timer_base+0x120/0x260 kernel/time/timer.c:946
       __mod_timer+0x1d6/0xeb0 kernel/time/timer.c:1019
       queue_delayed_work_on+0x156/0x250 kernel/workqueue.c:1715
       queue_delayed_work include/linux/workqueue.h:527 [inline]
       schedule_delayed_work include/linux/workqueue.h:631 [inline]
       kvfree_call_rcu+0x50e/0x8a0 kernel/rcu/tree.c:3625
       rtnl_register_internal+0x443/0x530 net/core/rtnetlink.c:223
       rtnl_register+0x32/0x70 net/core/rtnetlink.c:273
       ip_rt_init+0x2e6/0x3a0 net/ipv4/route.c:3791
       ip_init+0xa/0x20 net/ipv4/ip_output.c:1749
       inet_init+0x27c/0x390 net/ipv4/af_inet.c:2007
       do_one_initcall+0x22b/0x7a0 init/main.c:1302
       do_initcall_level+0x157/0x210 init/main.c:1375
       do_initcalls+0x49/0x90 init/main.c:1391
       kernel_init_freeable+0x425/0x5c0 init/main.c:1615
       kernel_init+0x19/0x290 init/main.c:1506
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #0 (krc.lock){..-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
       _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
       krc_this_cpu_lock kernel/rcu/tree.c:3199 [inline]
       add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline]
       kvfree_call_rcu+0x1b5/0x8a0 kernel/rcu/tree.c:3597
       trie_delete_elem+0x520/0x690
       bpf_prog_1db1603a7cfa36fb+0x3d/0xaf0
       bpf_dispatcher_nop_func include/linux/bpf.h:790 [inline]
       __bpf_prog_run include/linux/filter.h:628 [inline]
       bpf_prog_run include/linux/filter.h:635 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline]
       bpf_trace_run3+0x1d1/0x380 kernel/trace/bpf_trace.c:1916
       trace_timer_start include/trace/events/timer.h:52 [inline]
       enqueue_timer+0x3ae/0x540 kernel/time/timer.c:586
       internal_add_timer kernel/time/timer.c:611 [inline]
       __mod_timer+0xa60/0xeb0 kernel/time/timer.c:1062
       dsp_cmx_send+0x21bb/0x2240 drivers/isdn/mISDN/dsp_cmx.c:1850
       call_timer_fn+0x16d/0x560 kernel/time/timer.c:1451
       expire_timers kernel/time/timer.c:1496 [inline]
       __run_timers+0x67c/0x890 kernel/time/timer.c:1767
       run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
       handle_softirqs+0x3a7/0x930 kernel/softirq.c:558
       __do_softirq kernel/softirq.c:592 [inline]
       invoke_softirq kernel/softirq.c:432 [inline]
       __irq_exit_rcu+0x157/0x240 kernel/softirq.c:641
       irq_exit_rcu+0x5/0x20 kernel/softirq.c:653
       instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
       sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
       asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
       _raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194
       __debug_check_no_obj_freed lib/debugobjects.c:982 [inline]
       debug_check_no_obj_freed+0x455/0x4e0 lib/debugobjects.c:1003
       slab_free_hook mm/slub.c:1680 [inline]
       slab_free_freelist_hook+0x86/0x160 mm/slub.c:1731
       slab_free mm/slub.c:3499 [inline]
       kfree+0xf1/0x270 mm/slub.c:4559
       tomoyo_check_open_permission+0x373/0x490 security/tomoyo/file.c:786
       security_file_open+0x5f/0xa0 security/security.c:1668
       do_dentry_open+0x315/0xfb0 fs/open.c:813
       do_open fs/namei.c:3608 [inline]
       path_openat+0x2705/0x2f20 fs/namei.c:3742
       do_filp_open+0x21c/0x460 fs/namei.c:3769
       do_sys_openat2+0x13b/0x4f0 fs/open.c:1253
       do_sys_open fs/open.c:1269 [inline]
       __do_sys_openat fs/open.c:1285 [inline]
       __se_sys_openat fs/open.c:1280 [inline]
       __x64_sys_openat+0x243/0x290 fs/open.c:1280
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  krc.lock --> &base->lock --> &trie->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&trie->lock);
                               lock(&base->lock);
                               lock(&trie->lock);
  lock(krc.lock);

 *** DEADLOCK ***

6 locks held by udevd/3544:
 #0: ffffffff8d0ba318 (tomoyo_ss){....}-{0:0}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
 #1: ffffc90000dd0be0 ((&dsp_spl_tl)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
 #1: ffffc90000dd0be0 ((&dsp_spl_tl)){+.-.}-{0:0}, at: call_timer_fn+0xbe/0x560 kernel/time/timer.c:1441
 #2: ffffffff8d9f1f38 (dsp_lock){..-.}-{2:2}, at: dsp_cmx_send+0x22/0x2240 drivers/isdn/mISDN/dsp_cmx.c:1643
 #3: ffff8880b8f28098 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x120/0x260 kernel/time/timer.c:946
 #4: ffffffff8cb1f4e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
 #5: ffff888020c965b8 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467

stack backtrace:
CPU: 1 PID: 3544 Comm: udevd Not tainted 5.15.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 krc_this_cpu_lock kernel/rcu/tree.c:3199 [inline]
 add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline]
 kvfree_call_rcu+0x1b5/0x8a0 kernel/rcu/tree.c:3597
 trie_delete_elem+0x520/0x690
 bpf_prog_1db1603a7cfa36fb+0x3d/0xaf0
 bpf_dispatcher_nop_func include/linux/bpf.h:790 [inline]
 __bpf_prog_run include/linux/filter.h:628 [inline]
 bpf_prog_run include/linux/filter.h:635 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline]
 bpf_trace_run3+0x1d1/0x380 kernel/trace/bpf_trace.c:1916
 trace_timer_start include/trace/events/timer.h:52 [inline]
 enqueue_timer+0x3ae/0x540 kernel/time/timer.c:586
 internal_add_timer kernel/time/timer.c:611 [inline]
 __mod_timer+0xa60/0xeb0 kernel/time/timer.c:1062
 dsp_cmx_send+0x21bb/0x2240 drivers/isdn/mISDN/dsp_cmx.c:1850
 call_timer_fn+0x16d/0x560 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x67c/0x890 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x3a7/0x930 kernel/softirq.c:558
 __do_softirq kernel/softirq.c:592 [inline]
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x157/0x240 kernel/softirq.c:641
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:653
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194
Code: 9c 8f 44 24 20 42 80 3c 23 00 74 08 4c 89 f7 e8 72 f0 80 f7 f6 44 24 21 02 75 4e 41 f7 c7 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 97 00 0e f7 65 8b 05 08 d1 b8 75 85 c0 74 3f 48 c7 04 24 0e 36
RSP: 0018:ffffc90002dff420 EFLAGS: 00000206
RAX: 0845a49f76902800 RBX: 1ffff920005bfe88 RCX: ffffffff96a95f03
RDX: dffffc0000000000 RSI: ffffffff8aab2a60 RDI: 0000000000000001
RBP: ffffc90002dff4a8 R08: ffffffff81871b70 R09: fffffbfff2d90867
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: 1ffff920005bfe84 R14: ffffc90002dff440 R15: 0000000000000246
 __debug_check_no_obj_freed lib/debugobjects.c:982 [inline]
 debug_check_no_obj_freed+0x455/0x4e0 lib/debugobjects.c:1003
 slab_free_hook mm/slub.c:1680 [inline]
 slab_free_freelist_hook+0x86/0x160 mm/slub.c:1731
 slab_free mm/slub.c:3499 [inline]
 kfree+0xf1/0x270 mm/slub.c:4559
 tomoyo_check_open_permission+0x373/0x490 security/tomoyo/file.c:786
 security_file_open+0x5f/0xa0 security/security.c:1668
 do_dentry_open+0x315/0xfb0 fs/open.c:813
 do_open fs/namei.c:3608 [inline]
 path_openat+0x2705/0x2f20 fs/namei.c:3742
 do_filp_open+0x21c/0x460 fs/namei.c:3769
 do_sys_openat2+0x13b/0x4f0 fs/open.c:1253
 do_sys_open fs/open.c:1269 [inline]
 __do_sys_openat fs/open.c:1285 [inline]
 __se_sys_openat fs/open.c:1280 [inline]
 __x64_sys_openat+0x243/0x290 fs/open.c:1280
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7ff91aedb9a4
Code: 24 20 48 8d 44 24 30 48 89 44 24 28 64 8b 04 25 18 00 00 00 85 c0 75 2c 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 76 60 48 8b 15 55 a4 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffe8697d5c0 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00005640d735a040 RCX: 00007ff91aedb9a4
RDX: 0000000000080141 RSI: 00005640d733d0d8 RDI: 00000000ffffff9c
RBP: 00005640d733d0d8 R08: 00000000ffffffff R09: 0000000000000000
R10: 00000000000001a4 R11: 0000000000000246 R12: 0000000000080141
R13: ffffffffffffffff R14: 00000000ffffffff R15: 00000000ffffffff
 </TASK>
----------------
Code disassembly (best guess):
   0:	9c                   	pushf
   1:	8f 44 24 20          	pop    0x20(%rsp)
   5:	42 80 3c 23 00       	cmpb   $0x0,(%rbx,%r12,1)
   a:	74 08                	je     0x14
   c:	4c 89 f7             	mov    %r14,%rdi
   f:	e8 72 f0 80 f7       	call   0xf780f086
  14:	f6 44 24 21 02       	testb  $0x2,0x21(%rsp)
  19:	75 4e                	jne    0x69
  1b:	41 f7 c7 00 02 00 00 	test   $0x200,%r15d
  22:	74 01                	je     0x25
  24:	fb                   	sti
  25:	bf 01 00 00 00       	mov    $0x1,%edi
* 2a:	e8 97 00 0e f7       	call   0xf70e00c6 <-- trapping instruction
  2f:	65 8b 05 08 d1 b8 75 	mov    %gs:0x75b8d108(%rip),%eax        # 0x75b8d13e
  36:	85 c0                	test   %eax,%eax
  38:	74 3f                	je     0x79
  3a:	48                   	rex.W
  3b:	c7                   	.byte 0xc7
  3c:	04 24                	add    $0x24,%al
  3e:	0e                   	(bad)
  3f:	36                   	ss