======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc3-syzkaller-00762-g9268abe611b0 #0 Not tainted
------------------------------------------------------
syz.5.1818/12806 is trying to acquire lock:
ffffffff8fcb3988 (rtnl_mutex){+.+.}-{4:4}, at: ax25_setsockopt+0xa55/0xe90 net/ax25/af_ax25.c:680

but task is already holding lock:
ffff8880617ac258 (sk_lock-AF_AX25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1618 [inline]
ffff8880617ac258 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_setsockopt+0x209/0xe90 net/ax25/af_ax25.c:574

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+0x1ed/0x550 kernel/locking/lockdep.c:5849
       lock_sock_nested+0x48/0x100 net/core/sock.c:3642
       lock_sock include/net/sock.h:1618 [inline]
       ax25_kill_by_device net/ax25/af_ax25.c:101 [inline]
       ax25_device_event+0x24d/0x580 net/ax25/af_ax25.c:146
       notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85
       __dev_notify_flags+0x207/0x400
       dev_change_flags+0xf0/0x1a0 net/core/dev.c:9026
       dev_ifsioc+0x7c8/0xe70 net/core/dev_ioctl.c:563
       dev_ioctl+0x719/0x1340 net/core/dev_ioctl.c:820
       sock_do_ioctl+0x240/0x460 net/socket.c:1234
       sock_ioctl+0x626/0x8e0 net/socket.c:1339
       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 (rtnl_mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
       ax25_setsockopt+0xa55/0xe90 net/ax25/af_ax25.c:680
       do_sock_setsockopt+0x3af/0x720 net/socket.c:2324
       __sys_setsockopt net/socket.c:2349 [inline]
       __do_sys_setsockopt net/socket.c:2355 [inline]
       __se_sys_setsockopt net/socket.c:2352 [inline]
       __x64_sys_setsockopt+0x1ee/0x280 net/socket.c:2352
       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:

 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.5.1818/12806:
 #0: ffff8880617ac258 (sk_lock-AF_AX25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1618 [inline]
 #0: ffff8880617ac258 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_setsockopt+0x209/0xe90 net/ax25/af_ax25.c:574

stack backtrace:
CPU: 1 UID: 0 PID: 12806 Comm: syz.5.1818 Not tainted 6.13.0-rc3-syzkaller-00762-g9268abe611b0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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:2074
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
 ax25_setsockopt+0xa55/0xe90 net/ax25/af_ax25.c:680
 do_sock_setsockopt+0x3af/0x720 net/socket.c:2324
 __sys_setsockopt net/socket.c:2349 [inline]
 __do_sys_setsockopt net/socket.c:2355 [inline]
 __se_sys_setsockopt net/socket.c:2352 [inline]
 __x64_sys_setsockopt+0x1ee/0x280 net/socket.c:2352
 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: 0033:0x7f7b62385d29
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:00007f7b631f7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f7b62575fa0 RCX: 00007f7b62385d29
RDX: 0000000000000019 RSI: 0000000000000101 RDI: 0000000000000007
RBP: 00007f7b62401b08 R08: 0000000000000010 R09: 0000000000000000
R10: 0000000020000600 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f7b62575fa0 R15: 00007ffe72f4b8d8
 </TASK>
__nla_validate_parse: 6 callbacks suppressed
netlink: 28 bytes leftover after parsing attributes in process `syz.5.1818'.