====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.4.215/7824 is trying to acquire lock: ffff0000d4a49170 (&nr_node->node_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff0000d4a49170 (&nr_node->node_lock){+...}-{3:3}, at: nr_node_lock include/net/netrom.h:152 [inline] ffff0000d4a49170 (&nr_node->node_lock){+...}-{3:3}, at: nr_rt_device_down+0x128/0x660 net/netrom/nr_route.c:519 but task is already holding lock: ffff800092be1418 (nr_node_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff800092be1418 (nr_node_list_lock){+...}-{3:3}, at: nr_rt_device_down+0xb4/0x660 net/netrom/nr_route.c:517 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (nr_node_list_lock){+...}-{3:3}: __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x48/0x60 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_rt_device_down+0xb4/0x660 net/netrom/nr_route.c:517 nr_device_event+0x138/0x164 net/netrom/af_netrom.c:126 notifier_call_chain+0x1b8/0x4e4 kernel/notifier.c:85 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453 call_netdevice_notifiers_info net/core/dev.c:2229 [inline] call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] netif_close_many+0x2d4/0x448 net/core/dev.c:1784 netif_close+0x148/0x1f8 net/core/dev.c:1797 dev_close+0xf8/0x1e4 net/core/dev_api.c:220 bpq_device_event+0x380/0x68c drivers/net/hamradio/bpqether.c:528 notifier_call_chain+0x1b8/0x4e4 kernel/notifier.c:85 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453 call_netdevice_notifiers_info net/core/dev.c:2229 [inline] call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] __dev_notify_flags+0x260/0x47c net/core/dev.c:-1 netif_change_flags+0xd0/0x15c net/core/dev.c:9617 dev_change_flags+0x10c/0x204 net/core/dev_api.c:68 dev_ifsioc+0xd8/0xb90 net/core/dev_ioctl.c:579 dev_ioctl+0x4b0/0xc74 net/core/dev_ioctl.c:838 sock_do_ioctl+0x200/0x2b4 net/socket.c:1252 sock_ioctl+0x57c/0x84c net/socket.c:1359 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl fs/ioctl.c:584 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:584 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #1 (nr_neigh_list_lock){+...}-{3:3}: __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x48/0x60 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_remove_neigh+0x30/0xec net/netrom/nr_route.c:307 nr_add_node+0x19d0/0x21b0 net/netrom/nr_route.c:249 nr_rt_ioctl+0x904/0x9d8 net/netrom/nr_route.c:651 nr_ioctl+0x1c4/0x500 net/netrom/af_netrom.c:1254 sock_do_ioctl+0xf4/0x2b4 net/socket.c:1238 sock_ioctl+0x57c/0x84c net/socket.c:1359 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl fs/ioctl.c:584 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:584 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #0 (&nr_node->node_lock){+...}-{3:3}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x48/0x60 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_node_lock include/net/netrom.h:152 [inline] nr_rt_device_down+0x128/0x660 net/netrom/nr_route.c:519 nr_device_event+0x138/0x164 net/netrom/af_netrom.c:126 notifier_call_chain+0x1b8/0x4e4 kernel/notifier.c:85 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453 call_netdevice_notifiers_info net/core/dev.c:2229 [inline] call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] netif_close_many+0x2d4/0x448 net/core/dev.c:1784 netif_close+0x148/0x1f8 net/core/dev.c:1797 dev_close+0xf8/0x1e4 net/core/dev_api.c:220 bpq_device_event+0x380/0x68c drivers/net/hamradio/bpqether.c:528 notifier_call_chain+0x1b8/0x4e4 kernel/notifier.c:85 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453 call_netdevice_notifiers_info net/core/dev.c:2229 [inline] call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] __dev_notify_flags+0x260/0x47c net/core/dev.c:-1 netif_change_flags+0xd0/0x15c net/core/dev.c:9617 dev_change_flags+0x10c/0x204 net/core/dev_api.c:68 dev_ifsioc+0xd8/0xb90 net/core/dev_ioctl.c:579 dev_ioctl+0x4b0/0xc74 net/core/dev_ioctl.c:838 sock_do_ioctl+0x200/0x2b4 net/socket.c:1252 sock_ioctl+0x57c/0x84c net/socket.c:1359 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl fs/ioctl.c:584 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:584 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 other info that might help us debug this: Chain exists of: &nr_node->node_lock --> nr_neigh_list_lock --> nr_node_list_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(nr_node_list_lock); lock(nr_neigh_list_lock); lock(nr_node_list_lock); lock(&nr_node->node_lock); *** DEADLOCK *** 3 locks held by syz.4.215/7824: #0: ffff800092a8b228 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:80 #1: ffff800092be13b8 (nr_neigh_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] #1: ffff800092be13b8 (nr_neigh_list_lock){+...}-{3:3}, at: nr_rt_device_down+0x38/0x660 net/netrom/nr_route.c:514 #2: ffff800092be1418 (nr_node_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] #2: ffff800092be1418 (nr_node_list_lock){+...}-{3:3}, at: nr_rt_device_down+0xb4/0x660 net/netrom/nr_route.c:517 stack backtrace: CPU: 1 UID: 0 PID: 7824 Comm: syz.4.215 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2043 check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x48/0x60 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_node_lock include/net/netrom.h:152 [inline] nr_rt_device_down+0x128/0x660 net/netrom/nr_route.c:519 nr_device_event+0x138/0x164 net/netrom/af_netrom.c:126 notifier_call_chain+0x1b8/0x4e4 kernel/notifier.c:85 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453 call_netdevice_notifiers_info net/core/dev.c:2229 [inline] call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] netif_close_many+0x2d4/0x448 net/core/dev.c:1784 netif_close+0x148/0x1f8 net/core/dev.c:1797 dev_close+0xf8/0x1e4 net/core/dev_api.c:220 bpq_device_event+0x380/0x68c drivers/net/hamradio/bpqether.c:528 notifier_call_chain+0x1b8/0x4e4 kernel/notifier.c:85 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453 call_netdevice_notifiers_info net/core/dev.c:2229 [inline] call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] __dev_notify_flags+0x260/0x47c net/core/dev.c:-1 netif_change_flags+0xd0/0x15c net/core/dev.c:9617 dev_change_flags+0x10c/0x204 net/core/dev_api.c:68 dev_ifsioc+0xd8/0xb90 net/core/dev_ioctl.c:579 dev_ioctl+0x4b0/0xc74 net/core/dev_ioctl.c:838 sock_do_ioctl+0x200/0x2b4 net/socket.c:1252 sock_ioctl+0x57c/0x84c net/socket.c:1359 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl fs/ioctl.c:584 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:584 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596