======================================================
WARNING: possible circular locking dependency detected
5.15.189-syzkaller #0 Not tainted
------------------------------------------------------
syz.1.759/5160 is trying to acquire lock:
ffffffff8d36d418 (nr_neigh_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
ffffffff8d36d418 (nr_neigh_list_lock){+...}-{2:2}, at: nr_remove_neigh net/netrom/nr_route.c:307 [inline]
ffffffff8d36d418 (nr_neigh_list_lock){+...}-{2:2}, at: nr_del_node+0x512/0x8d0 net/netrom/nr_route.c:342
but task is already holding lock:
ffff888024445870 (&nr_node->node_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
ffff888024445870 (&nr_node->node_lock){+...}-{2:2}, at: nr_node_lock include/net/netrom.h:151 [inline]
ffff888024445870 (&nr_node->node_lock){+...}-{2:2}, at: nr_del_node+0x152/0x8d0 net/netrom/nr_route.c:335
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&nr_node->node_lock){+...}-{2:2}:
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x32/0x50 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+0x126/0x710 net/netrom/nr_route.c:519
nr_device_event+0x133/0x140 net/netrom/af_netrom.c:126
notifier_call_chain kernel/notifier.c:83 [inline]
raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
call_netdevice_notifiers net/core/dev.c:2075 [inline]
__dev_notify_flags+0x178/0x2d0 net/core/dev.c:-1
dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
dev_ifsioc+0x147/0xe70 net/core/dev_ioctl.c:324
dev_ioctl+0x55f/0xe50 net/core/dev_ioctl.c:587
sock_do_ioctl+0x222/0x2f0 net/socket.c:1154
sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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 (nr_node_list_lock){+...}-{2:2}:
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x32/0x50 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
nr_rt_device_down+0xa5/0x710 net/netrom/nr_route.c:517
nr_device_event+0x133/0x140 net/netrom/af_netrom.c:126
notifier_call_chain kernel/notifier.c:83 [inline]
raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
call_netdevice_notifiers net/core/dev.c:2075 [inline]
__dev_notify_flags+0x178/0x2d0 net/core/dev.c:-1
dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
dev_ifsioc+0x147/0xe70 net/core/dev_ioctl.c:324
dev_ioctl+0x55f/0xe50 net/core/dev_ioctl.c:587
sock_do_ioctl+0x222/0x2f0 net/socket.c:1154
sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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 (nr_neigh_list_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_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x32/0x50 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
nr_remove_neigh net/netrom/nr_route.c:307 [inline]
nr_del_node+0x512/0x8d0 net/netrom/nr_route.c:342
nr_rt_ioctl+0x982/0xce0 net/netrom/nr_route.c:678
sock_do_ioctl+0xd3/0x2f0 net/socket.c:1140
sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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:
nr_neigh_list_lock --> nr_node_list_lock --> &nr_node->node_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&nr_node->node_lock);
lock(nr_node_list_lock);
lock(&nr_node->node_lock);
lock(nr_neigh_list_lock);
*** DEADLOCK ***
2 locks held by syz.1.759/5160:
#0: ffffffff8d36d478 (nr_node_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
#0: ffffffff8d36d478 (nr_node_list_lock){+...}-{2:2}, at: nr_del_node+0xfc/0x8d0 net/netrom/nr_route.c:334
#1: ffff888024445870 (&nr_node->node_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
#1: ffff888024445870 (&nr_node->node_lock){+...}-{2:2}, at: nr_node_lock include/net/netrom.h:151 [inline]
#1: ffff888024445870 (&nr_node->node_lock){+...}-{2:2}, at: nr_del_node+0x152/0x8d0 net/netrom/nr_route.c:335
stack backtrace:
CPU: 1 PID: 5160 Comm: syz.1.759 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
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_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x32/0x50 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
nr_remove_neigh net/netrom/nr_route.c:307 [inline]
nr_del_node+0x512/0x8d0 net/netrom/nr_route.c:342
nr_rt_ioctl+0x982/0xce0 net/netrom/nr_route.c:678
sock_do_ioctl+0xd3/0x2f0 net/socket.c:1140
sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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: 0033:0x7f055ec269a9
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:00007ffda3395a58 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f055ee4dfa0 RCX: 00007f055ec269a9
RDX: 0000200000000680 RSI: 000000000000890c RDI: 0000000000000005
RBP: 00007f055eca8d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f055ee4dfa0 R14: 00007f055ee4dfa0 R15: 0000000000000003
</TASK>