====================================================== WARNING: possible circular locking dependency detected 6.14.0-rc1-syzkaller-00323-g2f4720318d02 #0 Not tainted ------------------------------------------------------ syz.1.1390/8807 is trying to acquire lock: ffffffff8fe14eb8 (nr_node_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffffffff8fe14eb8 (nr_node_list_lock){+...}-{3:3}, at: nr_rt_device_down+0xb5/0x7b0 net/netrom/nr_route.c:517 but task is already holding lock: ffffffff8fe14e58 (nr_neigh_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffffffff8fe14e58 (nr_neigh_list_lock){+...}-{3:3}, at: nr_rt_device_down+0x28/0x7b0 net/netrom/nr_route.c:514 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (nr_neigh_list_lock){+...}-{3:3}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_remove_neigh net/netrom/nr_route.c:307 [inline] nr_dec_obs net/netrom/nr_route.c:472 [inline] nr_rt_ioctl+0x398/0xfb0 net/netrom/nr_route.c:692 sock_do_ioctl+0x158/0x460 net/socket.c:1194 sock_ioctl+0x626/0x8e0 net/socket.c:1313 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&nr_node->node_lock){+...}-{3:3}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_node_lock include/net/netrom.h:152 [inline] nr_dec_obs net/netrom/nr_route.c:459 [inline] nr_rt_ioctl+0x192/0xfb0 net/netrom/nr_route.c:692 sock_do_ioctl+0x158/0x460 net/socket.c:1194 sock_ioctl+0x626/0x8e0 net/socket.c:1313 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (nr_node_list_lock){+...}-{3:3}: check_prev_add kernel/locking/lockdep.c:3163 [inline] check_prevs_add kernel/locking/lockdep.c:3282 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_rt_device_down+0xb5/0x7b0 net/netrom/nr_route.c:517 nr_device_event+0x134/0x150 net/netrom/af_netrom.c:126 notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85 __dev_notify_flags+0x207/0x400 dev_change_flags+0xf0/0x1a0 net/core/dev.c:9257 dev_ifsioc+0x7c8/0xe70 net/core/dev_ioctl.c:563 dev_ioctl+0x719/0x1340 net/core/dev_ioctl.c:826 sock_do_ioctl+0x240/0x460 net/socket.c:1208 sock_ioctl+0x626/0x8e0 net/socket.c:1313 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: nr_node_list_lock --> &nr_node->node_lock --> nr_neigh_list_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(nr_neigh_list_lock); lock(&nr_node->node_lock); lock(nr_neigh_list_lock); lock(nr_node_list_lock); *** DEADLOCK *** 2 locks held by syz.1.1390/8807: #0: ffffffff8fcc0388 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8fcc0388 (rtnl_mutex){+.+.}-{4:4}, at: dev_ioctl+0x706/0x1340 net/core/dev_ioctl.c:825 #1: ffffffff8fe14e58 (nr_neigh_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] #1: ffffffff8fe14e58 (nr_neigh_list_lock){+...}-{3:3}, at: nr_rt_device_down+0x28/0x7b0 net/netrom/nr_route.c:514 stack backtrace: CPU: 1 UID: 0 PID: 8807 Comm: syz.1.1390 Not tainted 6.14.0-rc1-syzkaller-00323-g2f4720318d02 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2076 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208 check_prev_add kernel/locking/lockdep.c:3163 [inline] check_prevs_add kernel/locking/lockdep.c:3282 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_rt_device_down+0xb5/0x7b0 net/netrom/nr_route.c:517 nr_device_event+0x134/0x150 net/netrom/af_netrom.c:126 notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85 __dev_notify_flags+0x207/0x400 dev_change_flags+0xf0/0x1a0 net/core/dev.c:9257 dev_ifsioc+0x7c8/0xe70 net/core/dev_ioctl.c:563 dev_ioctl+0x719/0x1340 net/core/dev_ioctl.c:826 sock_do_ioctl+0x240/0x460 net/socket.c:1208 sock_ioctl+0x626/0x8e0 net/socket.c:1313 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fcae7d8cde9 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:00007fcae8bda038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fcae7fa6080 RCX: 00007fcae7d8cde9 RDX: 0000400000000000 RSI: 0000000000008914 RDI: 0000000000000007 RBP: 00007fcae7e0e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fcae7fa6080 R15: 00007ffd40b10f08