======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-execprog/4179 is trying to acquire lock:
ffff888075625a38 (&trie->lock){..-.}-{2:2}, at: trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467

but task is already holding lock:
ffff8880b91280d8 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x674/0xd20 kernel/time/timer.c:1043

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&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:3629
       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:3798
       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:1316
       do_initcall_level+0x137/0x1f0 init/main.c:1389
       do_initcalls+0x4b/0x90 init/main.c:1405
       kernel_init_freeable+0x3ce/0x560 init/main.c:1629
       kernel_init+0x19/0x1b0 init/main.c:1520
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #1 (krc.lock){..-.}-{2:2}:
       __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:3203 [inline]
       add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3510 [inline]
       kvfree_call_rcu+0x186/0x7c0 kernel/rcu/tree.c:3601
       trie_update_elem+0x86e/0xc50 kernel/bpf/lpm_trie.c:396
       bpf_map_update_value+0x57d/0x650 kernel/bpf/syscall.c:223
       generic_map_update_batch+0x525/0x7c0 kernel/bpf/syscall.c:1430
       bpf_map_do_batch+0x466/0x600 kernel/bpf/syscall.c:-1
       __sys_bpf+0x601/0x670 kernel/bpf/syscall.c:-1
       __do_sys_bpf kernel/bpf/syscall.c:4761 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:4759 [inline]
       __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759
       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

-> #0 (&trie->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_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_5186c38a4019a4cb+0x42/0x148
       bpf_dispatcher_nop_func include/linux/bpf.h:888 [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:3142
       tcp_rcv_established+0x12bb/0x1cb0 net/ipv4/tcp_input.c:6033
       tcp_v4_do_rcv+0x44b/0x9b0 net/ipv4/tcp_ipv4.c:1731
       tcp_v4_rcv+0x268f/0x2cb0 net/ipv4/tcp_ipv4.c:2143
       ip_protocol_deliver_rcu+0x3ad/0x770 net/ipv4/ip_input.c:204
       ip_local_deliver_finish+0x1d5/0x320 net/ipv4/ip_input.c:231
       NF_HOOK+0x2d6/0x360 include/linux/netfilter.h:302
       NF_HOOK+0x2d6/0x360 include/linux/netfilter.h:302
       __netif_receive_skb_one_core net/core/dev.c:5525 [inline]
       __netif_receive_skb+0xcc/0x290 net/core/dev.c:5639
       process_backlog+0x364/0x780 net/core/dev.c:6516
       __napi_poll+0xc0/0x430 net/core/dev.c:7075
       napi_poll net/core/dev.c:7142 [inline]
       net_rx_action+0x4a8/0x9c0 net/core/dev.c:7232
       handle_softirqs+0x328/0x820 kernel/softirq.c:576
       do_softirq+0x13b/0x200 kernel/softirq.c:477
       __local_bh_enable_ip+0x174/0x1b0 kernel/softirq.c:401
       rcu_read_unlock_bh include/linux/rcupdate.h:810 [inline]
       ip_finish_output2+0xd32/0x1080 net/ipv4/ip_output.c:229
       dst_output include/net/dst.h:452 [inline]
       ip_local_out net/ipv4/ip_output.c:126 [inline]
       __ip_queue_xmit+0x11c3/0x1c00 net/ipv4/ip_output.c:532
       __tcp_transmit_skb+0x1ced/0x31c0 net/ipv4/tcp_output.c:1404
       tcp_transmit_skb net/ipv4/tcp_output.c:1422 [inline]
       tcp_write_xmit+0x1907/0x6590 net/ipv4/tcp_output.c:2707
       __tcp_push_pending_frames+0x92/0x250 net/ipv4/tcp_output.c:2892
       tcp_sendmsg_locked+0x2d96/0x3590 net/ipv4/tcp.c:1429
       tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1457
       sock_sendmsg_nosec net/socket.c:704 [inline]
       __sock_sendmsg net/socket.c:716 [inline]
       sock_write_iter+0x29c/0x380 net/socket.c:1079
       call_write_iter include/linux/fs.h:2172 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x712/0xd00 fs/read_write.c:594
       ksys_write+0x14d/0x250 fs/read_write.c:647
       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

other info that might help us debug this:

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

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

7 locks held by syz-execprog/4179:
 #0: ffff888079388120 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1730 [inline]
 #0: ffff888079388120 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_sendmsg+0x1d/0x40 net/ipv4/tcp.c:1456
 #1: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #2: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #3: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
 #4: ffff888024e10ca0 (slock-AF_INET/1){+.-.}-{2:2}, at: tcp_v4_rcv+0x261d/0x2cb0 net/ipv4/tcp_ipv4.c:2137
 #5: ffff8880b91280d8 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x674/0xd20 kernel/time/timer.c:1043
 #6: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312

stack backtrace:
CPU: 1 PID: 4179 Comm: syz-execprog Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <IRQ>
 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_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_5186c38a4019a4cb+0x42/0x148
 bpf_dispatcher_nop_func include/linux/bpf.h:888 [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:3142
 tcp_rcv_established+0x12bb/0x1cb0 net/ipv4/tcp_input.c:6033
 tcp_v4_do_rcv+0x44b/0x9b0 net/ipv4/tcp_ipv4.c:1731
 tcp_v4_rcv+0x268f/0x2cb0 net/ipv4/tcp_ipv4.c:2143
 ip_protocol_deliver_rcu+0x3ad/0x770 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x1d5/0x320 net/ipv4/ip_input.c:231
 NF_HOOK+0x2d6/0x360 include/linux/netfilter.h:302
 NF_HOOK+0x2d6/0x360 include/linux/netfilter.h:302
 __netif_receive_skb_one_core net/core/dev.c:5525 [inline]
 __netif_receive_skb+0xcc/0x290 net/core/dev.c:5639
 process_backlog+0x364/0x780 net/core/dev.c:6516
 __napi_poll+0xc0/0x430 net/core/dev.c:7075
 napi_poll net/core/dev.c:7142 [inline]
 net_rx_action+0x4a8/0x9c0 net/core/dev.c:7232
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 do_softirq+0x13b/0x200 kernel/softirq.c:477
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x174/0x1b0 kernel/softirq.c:401
 rcu_read_unlock_bh include/linux/rcupdate.h:810 [inline]
 ip_finish_output2+0xd32/0x1080 net/ipv4/ip_output.c:229
 dst_output include/net/dst.h:452 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 __ip_queue_xmit+0x11c3/0x1c00 net/ipv4/ip_output.c:532
 __tcp_transmit_skb+0x1ced/0x31c0 net/ipv4/tcp_output.c:1404
 tcp_transmit_skb net/ipv4/tcp_output.c:1422 [inline]
 tcp_write_xmit+0x1907/0x6590 net/ipv4/tcp_output.c:2707
 __tcp_push_pending_frames+0x92/0x250 net/ipv4/tcp_output.c:2892
 tcp_sendmsg_locked+0x2d96/0x3590 net/ipv4/tcp.c:1429
 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1457
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 sock_write_iter+0x29c/0x380 net/socket.c:1079
 call_write_iter include/linux/fs.h:2172 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x712/0xd00 fs/read_write.c:594
 ksys_write+0x14d/0x250 fs/read_write.c:647
 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
RIP: 0033:0x40dd0e
Code: 24 28 44 8b 44 24 2c e9 70 ff ff ff cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 49 89 f2 48 89 fa 48 89 ce 48 89 df 0f 05 <48> 3d 01 f0 ff ff 76 15 48 f7 d8 48 89 c1 48 c7 c0 ff ff ff ff 48
RSP: 002b:000000c003dbd3e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 000000000040dd0e
RDX: 00000000000004a8 RSI: 000000c004039058 RDI: 0000000000000006
RBP: 000000c003dbd428 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 000000c003dbd558
R13: 00000000000005f6 R14: 000000c001b54e00 R15: 000000c004038a80
 </TASK>