syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.180-syzkaller #0 Not tainted
------------------------------------------------------
syz.2.80/4632 is trying to acquire lock:
ffffffff8dc44008 (rtnl_mutex){+.+.}-{3:3}, at: ax25_setsockopt+0xa3a/0xe70 net/ax25/af_ax25.c:676

but task is already holding lock:
ffff88807a15e120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1684 [inline]
ffff88807a15e120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_setsockopt+0x206/0xe70 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_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       lock_sock_nested+0x44/0x100 net/core/sock.c:3253
       lock_sock include/net/sock.h:1684 [inline]
       ax25_kill_by_device net/ax25/af_ax25.c:99 [inline]
       ax25_device_event+0x239/0x510 net/ax25/af_ax25.c:142
       notifier_call_chain kernel/notifier.c:83 [inline]
       raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:391
       call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
       call_netdevice_notifiers net/core/dev.c:2075 [inline]
       dev_close_many+0x32c/0x4b0 net/core/dev.c:1650
       dev_close+0x1b3/0x2b0 net/core/dev.c:1672
       bpq_device_event+0x3c8/0x9d0 drivers/net/hamradio/bpqether.c:548
       notifier_call_chain kernel/notifier.c:83 [inline]
       raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:391
       call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
       call_netdevice_notifiers net/core/dev.c:2075 [inline]
       dev_close_many+0x32c/0x4b0 net/core/dev.c:1650
       dev_close+0x1b3/0x2b0 net/core/dev.c:1672
       bond_setup_by_slave+0x66/0x390 drivers/net/bonding/bond_main.c:1471
       bond_enslave+0x7b1/0x3c20 drivers/net/bonding/bond_main.c:1855
       bond_do_ioctl+0x2a6/0xb40 drivers/net/bonding/bond_main.c:4238
       dev_ifsioc+0xd15/0x1050 net/core/dev_ioctl.c:417
       dev_ioctl+0x512/0xf00 net/core/dev_ioctl.c:587
       sock_do_ioctl+0x27a/0x430 net/socket.c:1154
       sock_ioctl+0x484/0x770 net/socket.c:1257
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #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+0x1649/0x5930 kernel/locking/lockdep.c:3788
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       ax25_setsockopt+0xa3a/0xe70 net/ax25/af_ax25.c:676
       __sys_setsockopt+0x524/0x940 net/socket.c:2203
       __do_sys_setsockopt net/socket.c:2214 [inline]
       __se_sys_setsockopt net/socket.c:2211 [inline]
       __x64_sys_setsockopt+0xb1/0xc0 net/socket.c:2211
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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.2.80/4632:
 #0: ffff88807a15e120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1684 [inline]
 #0: ffff88807a15e120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_setsockopt+0x206/0xe70 net/ax25/af_ax25.c:570

stack backtrace:
CPU: 0 PID: 4632 Comm: syz.2.80 Not tainted 5.15.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x3b0 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+0x1649/0x5930 kernel/locking/lockdep.c:3788
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 ax25_setsockopt+0xa3a/0xe70 net/ax25/af_ax25.c:676
 __sys_setsockopt+0x524/0x940 net/socket.c:2203
 __do_sys_setsockopt net/socket.c:2214 [inline]
 __se_sys_setsockopt net/socket.c:2211 [inline]
 __x64_sys_setsockopt+0xb1/0xc0 net/socket.c:2211
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f160e8f9169
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:00007f160c761038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f160eb20fa0 RCX: 00007f160e8f9169
RDX: 0000000000000019 RSI: 0000000000000101 RDI: 0000000000000004
RBP: 00007f160e97ba68 R08: 0000000000000010 R09: 0000000000000000
R10: 00002000000000c0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f160eb20fa0 R15: 00007fff519bf868
 </TASK>