possible deadlock in nr_rt_device

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	possible deadlock in nr_rt_device_down (3) prio:low hams	4	C	error	error	16483	35d	625d	0/29	upstream: reported C repro on 2024/09/14 18:32
linux-6.1	possible deadlock in nr_rt_device_down origin:upstream	4	C		error	82	38d	516d	0/3	upstream: reported C repro on 2025/01/01 09:10
linux-5.15	possible deadlock in nr_rt_device_down origin:upstream	4	C		error	90	29d	750d	0/3	upstream: reported C repro on 2024/05/12 01:54
linux-6.6	possible deadlock in nr_rt_device_down origin:upstream missing-backport	4	syz		error	23	7d21h	327d	0/2	upstream: reported syz repro on 2025/07/09 16:09

====================================================== WARNING: possible circular locking dependency detected 6.10.0-syzkaller-12562-g1722389b0d86 #0 Not tainted ------------------------------------------------------ syz.0.2901/14000 is trying to acquire lock: ffffffff8fbdbcd8 (nr_node_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffffffff8fbdbcd8 (nr_node_list_lock){+...}-{2:2}, at: nr_rt_device_down+0xb5/0x7b0 net/netrom/nr_route.c:517 but task is already holding lock: ffffffff8fbdbc78 (nr_neigh_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffffffff8fbdbc78 (nr_neigh_list_lock){+...}-{2:2}, 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){+...}-{2:2}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759 __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:1222 sock_ioctl+0x629/0x8e0 net/socket.c:1341 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 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){+...}-{2:2}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759 __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:1222 sock_ioctl+0x629/0x8e0 net/socket.c:1341 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 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){+...}-{2:2}: check_prev_add kernel/locking/lockdep.c:3133 [inline] check_prevs_add kernel/locking/lockdep.c:3252 [inline] validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3868 __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759 __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+0x19f/0x3e0 kernel/notifier.c:93 __dev_notify_flags+0x207/0x400 dev_change_flags+0xf0/0x1a0 net/core/dev.c:8914 dev_ifsioc+0x7c8/0xe70 net/core/dev_ioctl.c:527 dev_ioctl+0x719/0x1340 net/core/dev_ioctl.c:784 sock_do_ioctl+0x240/0x460 net/socket.c:1236 sock_ioctl+0x629/0x8e0 net/socket.c:1341 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 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.0.2901/14000: #0: ffffffff8fa7f788 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x706/0x1340 net/core/dev_ioctl.c:783 #1: ffffffff8fbdbc78 (nr_neigh_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] #1: ffffffff8fbdbc78 (nr_neigh_list_lock){+...}-{2:2}, at: nr_rt_device_down+0x28/0x7b0 net/netrom/nr_route.c:514 stack backtrace: CPU: 0 UID: 0 PID: 14000 Comm: syz.0.2901 Not tainted 6.10.0-syzkaller-12562-g1722389b0d86 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2186 check_prev_add kernel/locking/lockdep.c:3133 [inline] check_prevs_add kernel/locking/lockdep.c:3252 [inline] validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3868 __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759 __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+0x19f/0x3e0 kernel/notifier.c:93 __dev_notify_flags+0x207/0x400 dev_change_flags+0xf0/0x1a0 net/core/dev.c:8914 dev_ifsioc+0x7c8/0xe70 net/core/dev_ioctl.c:527 dev_ioctl+0x719/0x1340 net/core/dev_ioctl.c:784 sock_do_ioctl+0x240/0x460 net/socket.c:1236 sock_ioctl+0x629/0x8e0 net/socket.c:1341 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 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: 0033:0x7f7784377299 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:00007f77850d3048 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f7784506130 RCX: 00007f7784377299 RDX: 0000000020000000 RSI: 0000000000008914 RDI: 0000000000000004 RBP: 00007f77843e48e6 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000006e R14: 00007f7784506130 R15: 00007ffd379f78c8 </TASK>

Crashes (2):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Assets (help?)	Manager	Title
2024/07/27 01:45	net-next	1722389b0d86	46eb10b7	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-net-kasan-gce	possible deadlock in nr_rt_device_down
2024/07/27 01:42	net-next	1722389b0d86	46eb10b7	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-net-kasan-gce	possible deadlock in nr_rt_device_down

Crashes (2):

Assets (help?)