syzbot


possible deadlock in nr_remove_neigh (2)

Status: upstream: reported C repro on 2024/12/30 02:36
Subsystems: hams
[Documentation on labels]
Reported-by: syzbot+8863ad36d31449b4dc17@syzkaller.appspotmail.com
First crash: 260d, last: 5h42m
Cause bisection: introduced by (bisect log) [merge commit]:
commit af96134dc8562f9fcbb8358af36f6086619a29ab
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Tue Jun 27 17:37:01 2023 +0000

  Merge tag 'rcu.2023.06.22a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Crash: possible deadlock in nr_remove_neigh (log)
Repro: C syz .config
  
Discussions (8)
Title Replies (including bot) Last reply
[syzbot] Monthly hams report (Aug 2025) 0 (1) 2025/08/25 08:40
[syzbot] Monthly hams report (Jul 2025) 0 (1) 2025/07/23 10:08
[syzbot] Monthly hams report (Jun 2025) 0 (1) 2025/06/23 07:31
[syzbot] Monthly hams report (May 2025) 0 (1) 2025/05/21 14:55
[syzbot] Monthly hams report (Apr 2025) 0 (1) 2025/04/22 10:11
[syzbot] Monthly hams report (Mar 2025) 0 (1) 2025/03/19 21:27
[syzbot] [hams?] possible deadlock in nr_remove_neigh (2) 2 (6) 2025/02/09 00:51
[syzbot] Monthly hams report (Jan 2025) 0 (1) 2025/01/16 10:12
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in nr_remove_neigh origin:upstream 4 C error 23 41d 233d 0/3 upstream: reported C repro on 2025/01/22 07:32
linux-6.1 possible deadlock in nr_remove_neigh 4 13 129d 256d 0/3 auto-obsoleted due to no activity on 2025/08/13 20:50
Last patch testing requests (3)
Created Duration User Patch Repo Result
2025/05/19 00:47 26m retest repro upstream report log
2025/02/08 23:45 46m hdanton@sina.com patch upstream OK log
2025/02/08 11:35 27m hdanton@sina.com patch upstream report log

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc1-syzkaller-00181-g7ee983c850b4 #0 Not tainted
------------------------------------------------------
syz-executor270/7031 is trying to acquire lock:
ffffffff90146478 (nr_neigh_list_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffffffff90146478 (nr_neigh_list_lock){+...}-{3:3}, at: nr_remove_neigh+0x1a/0x290 net/netrom/nr_route.c:307

but task is already holding lock:
ffff888145b6b970 (&nr_node->node_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff888145b6b970 (&nr_node->node_lock){+...}-{3:3}, at: nr_node_lock include/net/netrom.h:152 [inline]
ffff888145b6b970 (&nr_node->node_lock){+...}-{3:3}, at: nr_add_node+0x60b/0x2be0 net/netrom/nr_route.c:214

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&nr_node->node_lock){+...}-{3:3}:
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       nr_node_lock include/net/netrom.h:152 [inline]
       nr_rt_device_down+0x188/0x7f0 net/netrom/nr_route.c:519
       nr_device_event+0x126/0x170 net/netrom/af_netrom.c:126
       notifier_call_chain+0xb7/0x410 kernel/notifier.c:85
       call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2141
       call_netdevice_notifiers_extack net/core/dev.c:2179 [inline]
       call_netdevice_notifiers net/core/dev.c:2193 [inline]
       __dev_notify_flags+0x1f9/0x2e0 net/core/dev.c:9213
       dev_change_flags+0x10c/0x160 net/core/dev.c:9249
       dev_ifsioc+0x9d8/0x10d0 net/core/dev_ioctl.c:563
       dev_ioctl+0x224/0x10c0 net/core/dev_ioctl.c:826
       sock_do_ioctl+0x19e/0x280 net/socket.c:1213
       sock_ioctl+0x228/0x6c0 net/socket.c:1318
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (nr_node_list_lock){+...}-{3:3}:
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       nr_rt_device_down+0xd5/0x7f0 net/netrom/nr_route.c:517
       nr_device_event+0x126/0x170 net/netrom/af_netrom.c:126
       notifier_call_chain+0xb7/0x410 kernel/notifier.c:85
       call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2141
       call_netdevice_notifiers_extack net/core/dev.c:2179 [inline]
       call_netdevice_notifiers net/core/dev.c:2193 [inline]
       __dev_notify_flags+0x1f9/0x2e0 net/core/dev.c:9213
       dev_change_flags+0x10c/0x160 net/core/dev.c:9249
       dev_ifsioc+0x9d8/0x10d0 net/core/dev_ioctl.c:563
       dev_ioctl+0x224/0x10c0 net/core/dev_ioctl.c:826
       sock_do_ioctl+0x19e/0x280 net/socket.c:1213
       sock_ioctl+0x228/0x6c0 net/socket.c:1318
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (nr_neigh_list_lock){+...}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain kernel/locking/lockdep.c:3906 [inline]
       __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       nr_remove_neigh+0x1a/0x290 net/netrom/nr_route.c:307
       nr_add_node+0x23d1/0x2be0 net/netrom/nr_route.c:249
       nr_rt_ioctl+0x126e/0x29e0 net/netrom/nr_route.c:651
       nr_ioctl+0x19a/0x2e0 net/netrom/af_netrom.c:1254
       sock_do_ioctl+0x116/0x280 net/socket.c:1199
       sock_ioctl+0x228/0x6c0 net/socket.c:1318
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 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_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 ***

1 lock held by syz-executor270/7031:
 #0: ffff888145b6b970 (&nr_node->node_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #0: ffff888145b6b970 (&nr_node->node_lock){+...}-{3:3}, at: nr_node_lock include/net/netrom.h:152 [inline]
 #0: ffff888145b6b970 (&nr_node->node_lock){+...}-{3:3}, at: nr_add_node+0x60b/0x2be0 net/netrom/nr_route.c:214

stack backtrace:
CPU: 1 UID: 0 PID: 7031 Comm: syz-executor270 Not tainted 6.14.0-rc1-syzkaller-00181-g7ee983c850b4 #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+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x490/0x760 kernel/locking/lockdep.c:2076
 check_noncircular+0x31a/0x400 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 kernel/locking/lockdep.c:3906 [inline]
 __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
 _raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 nr_remove_neigh+0x1a/0x290 net/netrom/nr_route.c:307
 nr_add_node+0x23d1/0x2be0 net/netrom/nr_route.c:249
 nr_rt_ioctl+0x126e/0x29e0 net/netrom/nr_route.c:651
 nr_ioctl+0x19a/0x2e0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x116/0x280 net/socket.c:1199
 sock_ioctl+0x228/0x6c0 net/socket.c:1318
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcbef4bd2e9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 1f 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe540a63c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fcbef4bd2e9
RDX: 00002000000001c0 RSI: 000000000000890b RDI: 0000000000000008
RBP: 0000000000000000 R08: 00007ffe540a6400 R09: 00007ffe540a6400
R10: 00007ffe540a6400 R11: 0000000000000246 R12: 00007ffe540a63e8
R13: 00007ffe540a6420 R14: 00000000000000de R15: 431bde82d7b634db
 </TASK>

Crashes (361):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/08 05:01 upstream 7ee983c850b4 a4f327c2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in nr_remove_neigh
2025/07/21 20:28 upstream 89be9a83ccf1 0b3788a0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in nr_remove_neigh
2025/05/05 00:35 upstream e8ab83e34bdc b0714e37 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in nr_remove_neigh
2025/05/01 02:04 upstream b6ea1680d0ac ce7952f4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in nr_remove_neigh
2025/04/16 23:30 upstream c62f4b82d571 23b969b7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in nr_remove_neigh
2024/12/29 20:15 upstream 059dd502b263 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in nr_remove_neigh
2024/12/26 02:32 upstream 9b2ffa6148b1 444551c4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in nr_remove_neigh
2025/08/28 13:49 upstream 07d9df80082b bee60a83 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in nr_remove_neigh
2025/05/29 20:55 upstream e0797d3b91de 3d2f584d .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in nr_remove_neigh
2025/09/12 04:04 net 63a796558bc2 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/11 19:58 net 63a796558bc2 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/11 01:03 net 78dd8ad62cad fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/10 01:53 net e0d1c55501d3 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/09 07:29 net 1dbfb0363224 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/09 05:58 net 1dbfb0363224 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/08 21:47 net e2a10daba849 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/08 20:42 net e2a10daba849 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/07 07:05 net e2a10daba849 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/05 20:36 net 157cf360c4a8 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/05 16:52 net 157cf360c4a8 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/04 22:53 net 9b2bfdbf43ad d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/04 13:27 net c5142df58d5a d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/02 21:27 net a6099f263e1f 091ba174 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/02 15:39 net ba1e9421cf1a 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/01 22:34 net 0dffd938db37 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/01 10:49 net 788bc43d8330 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/31 16:25 net 788bc43d8330 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/30 17:39 net 788bc43d8330 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/30 08:09 net 9c736ace0666 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/30 04:50 net 9c736ace0666 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/30 03:38 net 9c736ace0666 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/30 01:18 net 9c736ace0666 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/21 23:01 net 1b78236a0593 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/21 20:14 net 1b78236a0593 0b9605c8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/20 17:07 net 51f27beeb79f bd178e57 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/20 15:17 net 51f27beeb79f bd178e57 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/20 03:29 net 01792bc3e5bd 79512909 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/19 11:58 net 864e3396976e 523f460e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/18 21:26 net 715c7a36d59f 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/17 16:46 net 715c7a36d59f 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/17 04:17 net 715c7a36d59f 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/08/17 01:23 net 715c7a36d59f 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in nr_remove_neigh
2025/09/10 15:23 net-next deb105f49879 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/09/05 08:56 net-next 16c610162d1f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/09/04 15:14 net-next 0e2a5208cc3d d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/09/04 06:26 net-next 0e2a5208cc3d d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/09/03 14:38 net-next 1d8f0059091e 96a211bc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/08/31 21:20 net-next 864ecc4a6dad 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/08/19 15:55 net-next da114122b831 523f460e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/08/19 15:54 net-next da114122b831 523f460e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/08/17 12:49 net-next bab3ce404553 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/08/16 12:15 net-next bab3ce404553 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in nr_remove_neigh
2025/04/14 22:16 linux-next 01c6df60d5d4 0bd6db41 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in nr_remove_neigh
2025/08/09 06:09 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 82af5ea7c611 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in nr_remove_neigh
* Struck through repros no longer work on HEAD.