IPv6: ADDRCONF(NETDEV_CHANGE): bpq0: link becomes ready
======================================================
WARNING: possible circular locking dependency detected
5.15.181-syzkaller #0 Not tainted
------------------------------------------------------
syz.1.31/4297 is trying to acquire lock:
ffff8000163aa5f8 (nr_neigh_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
ffff8000163aa5f8 (nr_neigh_list_lock){+...}-{2:2}, at: nr_remove_neigh net/netrom/nr_route.c:307 [inline]
ffff8000163aa5f8 (nr_neigh_list_lock){+...}-{2:2}, at: nr_del_node+0x368/0x8ec net/netrom/nr_route.c:342
but task is already holding lock:
ffff0000c89d4270 (&nr_node->node_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
ffff0000c89d4270 (&nr_node->node_lock){+...}-{2:2}, at: nr_node_lock include/net/netrom.h:151 [inline]
ffff0000c89d4270 (&nr_node->node_lock){+...}-{2:2}, at: nr_del_node+0xc0/0x8ec 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+0x114/0x1b4 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
nr_node_lock include/net/netrom.h:151 [inline]
nr_del_node+0xc0/0x8ec net/netrom/nr_route.c:335
nr_rt_ioctl+0x92c/0xe2c net/netrom/nr_route.c:678
nr_ioctl+0x1c4/0x51c net/netrom/af_netrom.c:1253
sock_do_ioctl+0xf8/0x240 net/socket.c:1140
sock_ioctl+0x5c8/0x87c 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+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
-> #1 (nr_node_list_lock){+...}-{2:2}:
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x114/0x1b4 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
nr_rt_device_down+0xb4/0x690 net/netrom/nr_route.c:517
nr_device_event+0x138/0x164 net/netrom/af_netrom.c:126
notifier_call_chain kernel/notifier.c:83 [inline]
raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:391
call_netdevice_notifiers_info net/core/dev.c:2049 [inline]
call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
call_netdevice_notifiers net/core/dev.c:2075 [inline]
__dev_notify_flags+0x250/0x46c net/core/dev.c:-1
dev_change_flags+0xc8/0x154 net/core/dev.c:8929
dev_ifsioc+0x504/0xef4 net/core/dev_ioctl.c:324
dev_ioctl+0x4d0/0xc94 net/core/dev_ioctl.c:587
sock_do_ioctl+0x18c/0x240 net/socket.c:1154
sock_ioctl+0x5c8/0x87c 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+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
-> #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+0x2928/0x651c kernel/locking/lockdep.c:5012
lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x114/0x1b4 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+0x368/0x8ec net/netrom/nr_route.c:342
nr_rt_ioctl+0x92c/0xe2c net/netrom/nr_route.c:678
nr_ioctl+0x1c4/0x51c net/netrom/af_netrom.c:1253
sock_do_ioctl+0xf8/0x240 net/socket.c:1140
sock_ioctl+0x5c8/0x87c 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+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/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:
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.1.31/4297:
#0: ffff8000163aa658 (nr_node_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
#0: ffff8000163aa658 (nr_node_list_lock){+...}-{2:2}, at: nr_del_node+0x60/0x8ec net/netrom/nr_route.c:334
#1: ffff0000c89d4270 (&nr_node->node_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
#1: ffff0000c89d4270 (&nr_node->node_lock){+...}-{2:2}, at: nr_node_lock include/net/netrom.h:151 [inline]
#1: ffff0000c89d4270 (&nr_node->node_lock){+...}-{2:2}, at: nr_del_node+0xc0/0x8ec net/netrom/nr_route.c:335
stack backtrace:
CPU: 0 PID: 4297 Comm: syz.1.31 Not tainted 5.15.181-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call trace:
dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
__dump_stack+0x30/0x40 lib/dump_stack.c:88
dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
dump_stack+0x1c/0x5c lib/dump_stack.c:113
print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2011
check_noncircular+0x240/0x2d4 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+0x2928/0x651c kernel/locking/lockdep.c:5012
lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x114/0x1b4 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+0x368/0x8ec net/netrom/nr_route.c:342
nr_rt_ioctl+0x92c/0xe2c net/netrom/nr_route.c:678
nr_ioctl+0x1c4/0x51c net/netrom/af_netrom.c:1253
sock_do_ioctl+0xf8/0x240 net/socket.c:1140
sock_ioctl+0x5c8/0x87c 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+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584