====================================================== WARNING: possible circular locking dependency detected 5.15.181-syzkaller #0 Not tainted ------------------------------------------------------ syz.0.73/4436 is trying to acquire lock: ffff8880b9127e78 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3199 [inline] ffff8880b9127e78 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3506 [inline] ffff8880b9127e78 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3597 but task is already holding lock: ffff88807904c5b8 (&trie->lock){....}-{2:2}, at: trie_delete_elem+0x90/0x710 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}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467 bpf_prog_e2f29814702bf05a+0x5ec/0xac4 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+0x17e/0x320 kernel/trace/bpf_trace.c:1916 trace_timer_start include/trace/events/timer.h:52 [inline] enqueue_timer+0x394/0x520 kernel/time/timer.c:586 internal_add_timer kernel/time/timer.c:611 [inline] __mod_timer+0x8e1/0xd20 kernel/time/timer.c:1062 sk_reset_timer+0x1f/0xb0 net/core/sock.c:3137 tipc_sk_finish_conn+0x154/0x7e0 net/tipc/socket.c:1675 tipc_socketpair+0x250/0x470 net/tipc/socket.c:3348 __sys_socketpair+0x2ac/0x540 net/socket.c:1659 __do_sys_socketpair net/socket.c:1695 [inline] __se_sys_socketpair net/socket.c:1692 [inline] __x64_sys_socketpair+0x97/0xb0 net/socket.c:1692 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #1 (&base->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 lock_timer_base+0x123/0x270 kernel/time/timer.c:946 __mod_timer+0x117/0xd20 kernel/time/timer.c:1019 queue_delayed_work_on+0x126/0x1e0 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+0x4a9/0x7c0 kernel/rcu/tree.c:3625 rtnl_register_internal+0x44e/0x540 net/core/rtnetlink.c:223 rtnl_register+0x2e/0x70 net/core/rtnetlink.c:273 ip_rt_init+0x2e0/0x3a0 net/ipv4/route.c:3791 ip_init+0xa/0x20 net/ipv4/ip_output.c:1749 inet_init+0x28b/0x3a0 net/ipv4/af_inet.c:2007 do_one_initcall+0x1ee/0x680 init/main.c:1302 do_initcall_level+0x137/0x1f0 init/main.c:1375 do_initcalls+0x4b/0x90 init/main.c:1391 kernel_init_freeable+0x3ce/0x560 init/main.c:1615 kernel_init+0x19/0x1b0 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 kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 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+0x186/0x7c0 kernel/rcu/tree.c:3597 trie_delete_elem+0x58c/0x710 kernel/bpf/lpm_trie.c:-1 bpf_prog_1db1603a7cfa36fb+0x3d/0x388 bpf_dispatcher_nop_func include/linux/bpf.h:790 [inline] __bpf_prog_run include/linux/filter.h:621 [inline] bpf_prog_run include/linux/filter.h:635 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline] bpf_trace_run1+0x23a/0x2d0 kernel/trace/bpf_trace.c:1914 trace_qdisc_destroy include/trace/events/qdisc.h:102 [inline] qdisc_destroy+0x338/0x390 net/sched/sch_generic.c:1030 qdisc_put net/sched/sch_generic.c:1044 [inline] dev_shutdown+0x5e6/0x710 net/sched/sch_generic.c:1408 unregister_netdevice_many+0xa0c/0x18f0 net/core/dev.c:11127 unregister_netdevice_queue+0x31c/0x360 net/core/dev.c:11067 unregister_netdevice include/linux/netdevice.h:3020 [inline] __tun_detach+0xd4a/0x1500 drivers/net/tun.c:686 tun_detach drivers/net/tun.c:702 [inline] tun_chr_close+0x109/0x1b0 drivers/net/tun.c:3440 __fput+0x234/0x930 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 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 *** 3 locks held by syz.0.73/4436: #0: ffffffff8d22a1c8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:699 [inline] #0: ffffffff8d22a1c8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3440 #1: ffffffff8c11be60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311 #2: ffff88807904c5b8 (&trie->lock){....}-{2:2}, at: trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467 stack backtrace: CPU: 1 PID: 4436 Comm: syz.0.73 Not tainted 5.15.181-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 check_noncircular+0x274/0x310 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 kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 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+0x186/0x7c0 kernel/rcu/tree.c:3597 trie_delete_elem+0x58c/0x710 kernel/bpf/lpm_trie.c:-1 bpf_prog_1db1603a7cfa36fb+0x3d/0x388 bpf_dispatcher_nop_func include/linux/bpf.h:790 [inline] __bpf_prog_run include/linux/filter.h:621 [inline] bpf_prog_run include/linux/filter.h:635 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline] bpf_trace_run1+0x23a/0x2d0 kernel/trace/bpf_trace.c:1914 trace_qdisc_destroy include/trace/events/qdisc.h:102 [inline] qdisc_destroy+0x338/0x390 net/sched/sch_generic.c:1030 qdisc_put net/sched/sch_generic.c:1044 [inline] dev_shutdown+0x5e6/0x710 net/sched/sch_generic.c:1408 unregister_netdevice_many+0xa0c/0x18f0 net/core/dev.c:11127 unregister_netdevice_queue+0x31c/0x360 net/core/dev.c:11067 unregister_netdevice include/linux/netdevice.h:3020 [inline] __tun_detach+0xd4a/0x1500 drivers/net/tun.c:686 tun_detach drivers/net/tun.c:702 [inline] tun_chr_close+0x109/0x1b0 drivers/net/tun.c:3440 __fput+0x234/0x930 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f71438c3969 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f714172b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 00007f7143aeafa0 RCX: 00007f71438c3969 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007f7143945ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f7143aeafa0 R15: 00007ffc626fd7c8