syzbot


possible deadlock in nr_rt_device_down (3)

Status: upstream: reported C repro on 2024/09/14 18:32
Subsystems: hams
[Documentation on labels]
Reported-by: syzbot+ccdfb85a561b973219c7@syzkaller.appspotmail.com
First crash: 161d, last: 9m
Cause bisection: failed (error log, bisect log)
  
Discussions (4)
Title Replies (including bot) Last reply
[syzbot] Monthly hams report (Feb 2025) 0 (1) 2025/02/16 21:54
[syzbot] [hams?] possible deadlock in nr_rt_device_down (3) 0 (3) 2025/02/11 02:23
[syzbot] Monthly hams report (Jan 2025) 0 (1) 2025/01/16 10:12
[syzbot] Monthly hams report (Nov 2024) 0 (1) 2024/11/15 10:49
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in nr_rt_device_down (2) hams 2 207d 207d 0/28 closed as invalid on 2024/09/04 18:18
linux-6.1 possible deadlock in nr_rt_device_down origin:upstream syz 33 10d 49d 0/3 upstream: reported syz repro on 2025/01/01 09:10
linux-5.15 possible deadlock in nr_rt_device_down origin:upstream C error 21 5d03h 283d 0/3 upstream: reported C repro on 2024/05/12 01:54

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc1-syzkaller-00206-g34c84b394890 #0 Not tainted
------------------------------------------------------
syz-executor309/5900 is trying to acquire lock:
ffffffff8fe14a38 (nr_node_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffffffff8fe14a38 (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:
ffffffff8fe149d8 (nr_neigh_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffffffff8fe149d8 (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-executor309/5900:
 #0: ffffffff8fcc0108 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8fcc0108 (rtnl_mutex){+.+.}-{4:4}, at: dev_ioctl+0x706/0x1340 net/core/dev_ioctl.c:825
 #1: ffffffff8fe149d8 (nr_neigh_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #1: ffffffff8fe149d8 (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: 5900 Comm: syz-executor309 Not tainted 6.14.0-rc1-syzkaller-00206-g34c84b394890 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __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: 0033:0x7f052c137829
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 1a 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcc38957c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f052c137829
RDX: 0000400000000000 RSI: 0000000000008914 RDI: 0000000000000007
RBP: 0000000000000000 R08: 00007f052c185214 R09: 00007f052c185214
R10: fffffffffffffe1d R11: 0000000000000246 R12: 00007f052c1854a8
R13: 00007f052c185084 R14: 00007ffcc3895800 R15: 0000000000000000
 </TASK>

Crashes (1882):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/11 02:22 net-next 34c84b394890 43f51a00 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2024/12/26 05:33 upstream 9b2ffa6148b1 444551c4 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in nr_rt_device_down
2025/02/13 13:50 net-next 2f4720318d02 2afad16e .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/19 09:35 upstream 6537cfb395f3 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in nr_rt_device_down
2025/02/19 08:21 upstream 6537cfb395f3 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in nr_rt_device_down
2025/02/07 08:24 upstream bb066fe812d6 53657d1b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in nr_rt_device_down
2025/02/05 10:54 upstream 5c8c229261f1 5896748e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in nr_rt_device_down
2025/01/10 02:16 upstream eea6e4b4dfb8 40f46913 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in nr_rt_device_down
2025/02/17 07:23 upstream ba643b6d8440 40a34ec9 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in nr_rt_device_down
2025/02/12 04:26 upstream 09fbf3d50205 f2baddf5 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in nr_rt_device_down
2025/02/19 06:39 net f7b5279b67e7 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/19 05:31 net f7b5279b67e7 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/19 01:25 net f7b5279b67e7 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/19 01:06 net f7b5279b67e7 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 21:58 net f7b5279b67e7 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 19:54 net 07b598c0e6f0 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 17:21 net 07b598c0e6f0 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 15:36 net 07b598c0e6f0 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 14:34 net 07b598c0e6f0 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 09:39 net 07b598c0e6f0 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 08:39 net 07b598c0e6f0 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 07:20 net 07b598c0e6f0 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 05:23 net 07b598c0e6f0 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 03:07 net 07b598c0e6f0 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 00:11 net 071ed42cff4f 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 23:43 net 071ed42cff4f 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 22:35 net 071ed42cff4f 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 20:19 net 071ed42cff4f 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 19:09 net 071ed42cff4f 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 17:44 net 071ed42cff4f 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 16:22 net 071ed42cff4f 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 15:10 net 071ed42cff4f 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 08:26 net 071ed42cff4f 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2024/09/10 18:26 net 4c8002277167 784df80e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_rt_device_down
2025/02/19 09:52 net-next 4991b88c2514 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/19 04:10 net-next 4991b88c2514 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/19 03:10 net-next 4991b88c2514 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 23:56 net-next 4991b88c2514 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 18:34 net-next dbcbec81c9b8 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 13:22 net-next dbcbec81c9b8 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 11:54 net-next dbcbec81c9b8 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 10:58 net-next dbcbec81c9b8 c37c7249 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 05:47 net-next dbcbec81c9b8 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/18 02:01 net-next dbcbec81c9b8 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 21:33 net-next 0784d83df3bf 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 19:19 net-next 0784d83df3bf 9be4ace3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 14:04 net-next 0784d83df3bf 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 12:29 net-next 0784d83df3bf 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 11:22 net-next 0784d83df3bf 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 09:37 net-next 0784d83df3bf 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 06:42 net-next 0784d83df3bf 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 05:22 net-next 0784d83df3bf 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/02/17 04:22 net-next 0784d83df3bf 40a34ec9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_rt_device_down
2025/01/06 13:46 linux-next 8155b4ef3466 f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in nr_rt_device_down
2025/01/18 01:08 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 1950a0af2d55 953d1c45 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in nr_rt_device_down
* Struck through repros no longer work on HEAD.