syzbot


possible deadlock in nr_remove_neigh

Status: upstream: reported on 2024/12/29 20:32
Reported-by: syzbot+3836715549cbc66fdedc@syzkaller.appspotmail.com
First crash: 6d03h, last: 6d03h
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in nr_remove_neigh (2) hams 16 2d17h 5d21h 0/28 upstream: reported on 2024/12/30 02:36

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.1.122-syzkaller #0 Tainted: G        W         
------------------------------------------------------
syz.6.665/7655 is trying to acquire lock:
ffffffff8e653178 (nr_neigh_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffffffff8e653178 (nr_neigh_list_lock){+...}-{2:2}, at: nr_remove_neigh+0x25/0xe0 net/netrom/nr_route.c:307

but task is already holding lock:
ffff88802400a470 (&nr_node->node_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff88802400a470 (&nr_node->node_lock){+...}-{2:2}, at: nr_node_lock include/net/netrom.h:152 [inline]
ffff88802400a470 (&nr_node->node_lock){+...}-{2:2}, at: nr_add_node+0xfc0/0x2210 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){+...}-{2:2}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x31/0x40 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+0x155/0x7b0 net/netrom/nr_route.c:519
       nr_device_event+0x12b/0x140 net/netrom/af_netrom.c:126
       notifier_call_chain kernel/notifier.c:87 [inline]
       raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:455
       call_netdevice_notifiers_info net/core/dev.c:1970 [inline]
       call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
       call_netdevice_notifiers net/core/dev.c:2022 [inline]
       dev_close_many+0x37c/0x530 net/core/dev.c:1570
       dev_close+0x1b3/0x2b0 net/core/dev.c:1592
       bpq_device_event+0x35f/0x8a0 drivers/net/hamradio/bpqether.c:547
       notifier_call_chain kernel/notifier.c:87 [inline]
       raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:455
       call_netdevice_notifiers_info net/core/dev.c:1970 [inline]
       call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
       call_netdevice_notifiers net/core/dev.c:2022 [inline]
       dev_close_many+0x37c/0x530 net/core/dev.c:1570
       dev_close+0x1b3/0x2b0 net/core/dev.c:1592
       bond_setup_by_slave+0x66/0x390 drivers/net/bonding/bond_main.c:1541
       bond_enslave+0x7b4/0x3ad0 drivers/net/bonding/bond_main.c:1925
       bond_do_ioctl+0x2a1/0xaf0 drivers/net/bonding/bond_main.c:4593
       dev_ifsioc+0xe2b/0x1160 net/core/dev_ioctl.c:420
       dev_ioctl+0x508/0xf70 net/core/dev_ioctl.c:588
       sock_do_ioctl+0x26b/0x450 net/socket.c:1218
       sock_ioctl+0x47f/0x770 net/socket.c:1321
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (nr_node_list_lock){+...}-{2:2}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       nr_rt_device_down+0xb1/0x7b0 net/netrom/nr_route.c:517
       nr_device_event+0x12b/0x140 net/netrom/af_netrom.c:126
       notifier_call_chain kernel/notifier.c:87 [inline]
       raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:455
       call_netdevice_notifiers_info net/core/dev.c:1970 [inline]
       call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
       call_netdevice_notifiers net/core/dev.c:2022 [inline]
       dev_close_many+0x37c/0x530 net/core/dev.c:1570
       dev_close+0x1b3/0x2b0 net/core/dev.c:1592
       bpq_device_event+0x35f/0x8a0 drivers/net/hamradio/bpqether.c:547
       notifier_call_chain kernel/notifier.c:87 [inline]
       raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:455
       call_netdevice_notifiers_info net/core/dev.c:1970 [inline]
       call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
       call_netdevice_notifiers net/core/dev.c:2022 [inline]
       dev_close_many+0x37c/0x530 net/core/dev.c:1570
       dev_close+0x1b3/0x2b0 net/core/dev.c:1592
       bond_setup_by_slave+0x66/0x390 drivers/net/bonding/bond_main.c:1541
       bond_enslave+0x7b4/0x3ad0 drivers/net/bonding/bond_main.c:1925
       bond_do_ioctl+0x2a1/0xaf0 drivers/net/bonding/bond_main.c:4593
       dev_ifsioc+0xe2b/0x1160 net/core/dev_ioctl.c:420
       dev_ioctl+0x508/0xf70 net/core/dev_ioctl.c:588
       sock_do_ioctl+0x26b/0x450 net/socket.c:1218
       sock_ioctl+0x47f/0x770 net/socket.c:1321
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (nr_neigh_list_lock){+...}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       nr_remove_neigh+0x25/0xe0 net/netrom/nr_route.c:307
       nr_add_node+0x14fd/0x2210 net/netrom/nr_route.c:249
       nr_rt_ioctl+0xd38/0xfb0 net/netrom/nr_route.c:651
       sock_do_ioctl+0x152/0x450 net/socket.c:1204
       sock_ioctl+0x47f/0x770 net/socket.c:1321
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

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.6.665/7655:
 #0: ffff88802400a470 (&nr_node->node_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #0: ffff88802400a470 (&nr_node->node_lock){+...}-{2:2}, at: nr_node_lock include/net/netrom.h:152 [inline]
 #0: ffff88802400a470 (&nr_node->node_lock){+...}-{2:2}, at: nr_add_node+0xfc0/0x2210 net/netrom/nr_route.c:214

stack backtrace:
CPU: 1 PID: 7655 Comm: syz.6.665 Tainted: G        W          6.1.122-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
 _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 nr_remove_neigh+0x25/0xe0 net/netrom/nr_route.c:307
 nr_add_node+0x14fd/0x2210 net/netrom/nr_route.c:249
 nr_rt_ioctl+0xd38/0xfb0 net/netrom/nr_route.c:651
 sock_do_ioctl+0x152/0x450 net/socket.c:1204
 sock_ioctl+0x47f/0x770 net/socket.c:1321
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe3b0d85d29
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:00007fe3b1c08038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe3b0f75fa0 RCX: 00007fe3b0d85d29
RDX: 0000000020000280 RSI: 000000000000890b RDI: 0000000000000004
RBP: 00007fe3b0e01b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe3b0f75fa0 R15: 00007ffeb8c3e8a8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/29 20:31 linux-6.1.y 563edd786f0a d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in nr_remove_neigh
* Struck through repros no longer work on HEAD.