====================================================== WARNING: possible circular locking dependency detected 5.15.158-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.2/6985 is trying to acquire lock: ffff0000dbf5ec70 (&nr_node->node_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline] ffff0000dbf5ec70 (&nr_node->node_lock){+...}-{2:2}, at: nr_node_lock include/net/netrom.h:151 [inline] ffff0000dbf5ec70 (&nr_node->node_lock){+...}-{2:2}, at: nr_rt_device_down+0x144/0x8fc net/netrom/nr_route.c:524 but task is already holding lock: ffff800016b6ad58 (nr_node_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline] ffff800016b6ad58 (nr_node_list_lock){+...}-{2:2}, at: nr_rt_device_down+0xb4/0x8fc net/netrom/nr_route.c:522 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (nr_node_list_lock){+...}-{2:2}: __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x124/0x1c4 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:368 [inline] nr_remove_node net/netrom/nr_route.c:299 [inline] nr_del_node net/netrom/nr_route.c:355 [inline] nr_rt_ioctl+0x13c4/0x1b0c net/netrom/nr_route.c:683 nr_ioctl+0x14c/0x4b0 net/netrom/af_netrom.c:1253 sock_do_ioctl+0x134/0x2dc net/socket.c:1140 sock_ioctl+0x4f0/0x8ac net/socket.c:1257 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #0 (&nr_node->node_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+0x32d4/0x7638 kernel/locking/lockdep.c:5012 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x124/0x1c4 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:368 [inline] nr_node_lock include/net/netrom.h:151 [inline] nr_rt_device_down+0x144/0x8fc net/netrom/nr_route.c:524 nr_device_event+0x134/0x160 net/netrom/af_netrom.c:126 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:391 __dev_notify_flags+0x2ac/0x534 dev_change_flags+0xc8/0x154 net/core/dev.c:8889 dev_ifsioc+0x140/0xfe4 net/core/dev_ioctl.c:324 dev_ioctl+0x4e0/0xd3c net/core/dev_ioctl.c:587 sock_do_ioctl+0x1dc/0x2dc net/socket.c:1154 sock_ioctl+0x4f0/0x8ac net/socket.c:1257 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(nr_node_list_lock); lock(&nr_node->node_lock); lock(nr_node_list_lock); lock(&nr_node->node_lock); *** DEADLOCK *** 3 locks held by syz-executor.2/6985: #0: ffff800016a36668 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:72 #1: ffff800016b6acf8 (nr_neigh_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline] #1: ffff800016b6acf8 (nr_neigh_list_lock){+...}-{2:2}, at: nr_rt_device_down+0x38/0x8fc net/netrom/nr_route.c:519 #2: ffff800016b6ad58 (nr_node_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline] #2: ffff800016b6ad58 (nr_node_list_lock){+...}-{2:2}, at: nr_rt_device_down+0xb4/0x8fc net/netrom/nr_route.c:522 stack backtrace: CPU: 0 PID: 6985 Comm: syz-executor.2 Not tainted 5.15.158-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Call trace: dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011 check_noncircular+0x2cc/0x378 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+0x32d4/0x7638 kernel/locking/lockdep.c:5012 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x124/0x1c4 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:368 [inline] nr_node_lock include/net/netrom.h:151 [inline] nr_rt_device_down+0x144/0x8fc net/netrom/nr_route.c:524 nr_device_event+0x134/0x160 net/netrom/af_netrom.c:126 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:391 __dev_notify_flags+0x2ac/0x534 dev_change_flags+0xc8/0x154 net/core/dev.c:8889 dev_ifsioc+0x140/0xfe4 net/core/dev_ioctl.c:324 dev_ioctl+0x4e0/0xd3c net/core/dev_ioctl.c:587 sock_do_ioctl+0x1dc/0x2dc net/socket.c:1154 sock_ioctl+0x4f0/0x8ac net/socket.c:1257 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584