syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.185-syzkaller #0 Not tainted
------------------------------------------------------
syz.5.636/6327 is trying to acquire lock:
ffff8000162886e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:72

but task is already holding lock:
ffff0000e8695120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1694 [inline]
ffff0000e8695120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_setsockopt+0x274/0xa5c net/ax25/af_ax25.c:570

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sk_lock-AF_AX25){+.+.}-{0:0}:
       lock_sock_nested+0xd8/0x1d4 net/core/sock.c:3251
       lock_sock include/net/sock.h:1694 [inline]
       ax25_kill_by_device net/ax25/af_ax25.c:99 [inline]
       ax25_device_event+0x20c/0x590 net/ax25/af_ax25.c:142
       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_close_many+0x2cc/0x440 net/core/dev.c:1650
       dev_close+0x148/0x1f8 net/core/dev.c:1672
       bpq_device_event+0x318/0x824 drivers/net/hamradio/bpqether.c:548
       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_close_many+0x2cc/0x440 net/core/dev.c:1650
       dev_close+0x148/0x1f8 net/core/dev.c:1672
       bond_setup_by_slave+0x70/0x318 drivers/net/bonding/bond_main.c:1471
       bond_enslave+0x624/0x3014 drivers/net/bonding/bond_main.c:1855
       bond_do_ioctl+0x6ec/0xb3c drivers/net/bonding/bond_main.c:4238
       dev_siocbond net/core/dev_ioctl.c:270 [inline]
       dev_ifsioc+0xc44/0xef4 net/core/dev_ioctl.c:417
       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 (rtnl_mutex){+.+.}-{3:3}:
       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
       __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743
       rtnl_lock+0x20/0x2c net/core/rtnetlink.c:72
       ax25_setsockopt+0x870/0xa5c net/ax25/af_ax25.c:676
       __sys_setsockopt+0x2f8/0x4b0 net/socket.c:2203
       __do_sys_setsockopt net/socket.c:2214 [inline]
       __se_sys_setsockopt net/socket.c:2211 [inline]
       __arm64_sys_setsockopt+0xb8/0xd4 net/socket.c:2211
       __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:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_AX25);
                               lock(rtnl_mutex);
                               lock(sk_lock-AF_AX25);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syz.5.636/6327:
 #0: ffff0000e8695120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1694 [inline]
 #0: ffff0000e8695120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_setsockopt+0x274/0xa5c net/ax25/af_ax25.c:570

stack backtrace:
CPU: 1 PID: 6327 Comm: syz.5.636 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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
 __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743
 rtnl_lock+0x20/0x2c net/core/rtnetlink.c:72
 ax25_setsockopt+0x870/0xa5c net/ax25/af_ax25.c:676
 __sys_setsockopt+0x2f8/0x4b0 net/socket.c:2203
 __do_sys_setsockopt net/socket.c:2214 [inline]
 __se_sys_setsockopt net/socket.c:2211 [inline]
 __arm64_sys_setsockopt+0xb8/0xd4 net/socket.c:2211
 __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