======================================================
WARNING: possible circular locking dependency detected
5.15.186-syzkaller #0 Not tainted
------------------------------------------------------
syz.5.1281/9463 is trying to acquire lock:
ffff888063b3f120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1694 [inline]
ffff888063b3f120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_kill_by_device net/ax25/af_ax25.c:99 [inline]
ffff888063b3f120 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_device_event+0x217/0x4f0 net/ax25/af_ax25.c:142

but task is already holding lock:
ffffffff8d22a808 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x54e/0xe50 net/core/dev_ioctl.c:586

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (rtnl_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x1eb/0x2390 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+0x830/0xa40 net/ax25/af_ax25.c:676
       __sys_setsockopt+0x3d6/0x5e0 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+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (sk_lock-AF_AX25){+.+.}-{0:0}:
       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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       lock_sock_nested+0x44/0x100 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+0x217/0x4f0 net/ax25/af_ax25.c:142
       notifier_call_chain kernel/notifier.c:83 [inline]
       raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
       call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
       call_netdevice_notifiers net/core/dev.c:2075 [inline]
       __dev_notify_flags+0x178/0x2d0 net/core/dev.c:-1
       dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
       dev_ifsioc+0x147/0xe70 net/core/dev_ioctl.c:324
       dev_ioctl+0x55f/0xe50 net/core/dev_ioctl.c:587
       sock_do_ioctl+0x222/0x2f0 net/socket.c:1154
       sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 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(rtnl_mutex);
                               lock(sk_lock-AF_AX25);
                               lock(rtnl_mutex);
  lock(sk_lock-AF_AX25);

 *** DEADLOCK ***

1 lock held by syz.5.1281/9463:
 #0: ffffffff8d22a808 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x54e/0xe50 net/core/dev_ioctl.c:586

stack backtrace:
CPU: 0 PID: 9463 Comm: syz.5.1281 Not tainted 5.15.186-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 lock_sock_nested+0x44/0x100 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+0x217/0x4f0 net/ax25/af_ax25.c:142
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
 call_netdevice_notifiers net/core/dev.c:2075 [inline]
 __dev_notify_flags+0x178/0x2d0 net/core/dev.c:-1
 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
 dev_ifsioc+0x147/0xe70 net/core/dev_ioctl.c:324
 dev_ioctl+0x55f/0xe50 net/core/dev_ioctl.c:587
 sock_do_ioctl+0x222/0x2f0 net/socket.c:1154
 sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fdb9ad76929
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:00007fdb98bde038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fdb9af9dfa0 RCX: 00007fdb9ad76929
RDX: 0000200000000000 RSI: 0000000000008914 RDI: 000000000000000a
RBP: 00007fdb9adf8b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fdb9af9dfa0 R15: 00007ffcf28e74d8
 </TASK>
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: use-after-free in atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:167 [inline]
BUG: KASAN: use-after-free in __refcount_sub_and_test include/linux/refcount.h:272 [inline]
BUG: KASAN: use-after-free in __refcount_dec_and_test include/linux/refcount.h:315 [inline]
BUG: KASAN: use-after-free in refcount_dec_and_test include/linux/refcount.h:333 [inline]
BUG: KASAN: use-after-free in ax25_dev_put include/net/ax25.h:301 [inline]
BUG: KASAN: use-after-free in ax25_dev_device_down+0x35e/0x520 net/ax25/ax25_dev.c:122
Write of size 4 at addr ffff8880637e3db8 by task syz.5.1281/9463

CPU: 1 PID: 9463 Comm: syz.5.1281 Not tainted 5.15.186-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x27b/0x290 mm/kasan/generic.c:189
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:167 [inline]
 __refcount_sub_and_test include/linux/refcount.h:272 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 ax25_dev_put include/net/ax25.h:301 [inline]
 ax25_dev_device_down+0x35e/0x520 net/ax25/ax25_dev.c:122
 ax25_device_event+0x4b4/0x4f0 net/ax25/af_ax25.c:144
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
 call_netdevice_notifiers net/core/dev.c:2075 [inline]
 __dev_notify_flags+0x178/0x2d0 net/core/dev.c:-1
 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
 dev_ifsioc+0x147/0xe70 net/core/dev_ioctl.c:324
 dev_ioctl+0x55f/0xe50 net/core/dev_ioctl.c:587
 sock_do_ioctl+0x222/0x2f0 net/socket.c:1154
 sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fdb9ad76929
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:00007fdb98bde038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fdb9af9dfa0 RCX: 00007fdb9ad76929
RDX: 0000200000000000 RSI: 0000000000008914 RDI: 000000000000000a
RBP: 00007fdb9adf8b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fdb9af9dfa0 R15: 00007ffcf28e74d8
 </TASK>

Allocated by task 4923:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:735 [inline]
 ax25_dev_device_up+0x50/0x580 net/ax25/ax25_dev.c:55
 ax25_device_event+0x483/0x4f0 net/ax25/af_ax25.c:139
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
 call_netdevice_notifiers net/core/dev.c:2075 [inline]
 __dev_notify_flags+0x178/0x2d0 net/core/dev.c:-1
 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
 dev_ifsioc+0x147/0xe70 net/core/dev_ioctl.c:324
 dev_ioctl+0x55f/0xe50 net/core/dev_ioctl.c:587
 sock_do_ioctl+0x222/0x2f0 net/socket.c:1154
 sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 9463:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1705 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1731
 slab_free mm/slub.c:3499 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4559
 ax25_dev_put include/net/ax25.h:302 [inline]
 ax25_dev_device_down+0x1c0/0x520 net/ax25/ax25_dev.c:119
 ax25_device_event+0x4b4/0x4f0 net/ax25/af_ax25.c:144
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
 call_netdevice_notifiers net/core/dev.c:2075 [inline]
 __dev_notify_flags+0x178/0x2d0 net/core/dev.c:-1
 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
 dev_ifsioc+0x147/0xe70 net/core/dev_ioctl.c:324
 dev_ioctl+0x55f/0xe50 net/core/dev_ioctl.c:587
 sock_do_ioctl+0x222/0x2f0 net/socket.c:1154
 sock_ioctl+0x4ed/0x6e0 net/socket.c:1257
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff8880637e3d00
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 184 bytes inside of
 192-byte region [ffff8880637e3d00, ffff8880637e3dc0)
The buggy address belongs to the page:
page:ffffea00018df8c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880637e3100 pfn:0x637e3
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00007f0988 ffffea000075a948 ffff888016841a00
raw: ffff8880637e3100 000000000010000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 4449, ts 76442135203, free_ts 76431691697
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5474
 alloc_slab_page mm/slub.c:1775 [inline]
 allocate_slab mm/slub.c:1912 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1975
 ___slab_alloc+0x81e/0xdf0 mm/slub.c:3008
 __slab_alloc mm/slub.c:3095 [inline]
 slab_alloc_node mm/slub.c:3186 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc_trace+0x1a5/0x2a0 mm/slub.c:3245
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:735 [inline]
 push_stack+0x90/0x510 kernel/bpf/verifier.c:1047
 check_cond_jmp_op kernel/bpf/verifier.c:9341 [inline]
 do_check+0xc414/0xeac0 kernel/bpf/verifier.c:11472
 do_check_common+0xe67/0x16c0 kernel/bpf/verifier.c:13485
 do_check_main kernel/bpf/verifier.c:13548 [inline]
 bpf_check+0x31f3/0xf090 kernel/bpf/verifier.c:14119
 bpf_prog_load+0x1043/0x1550 kernel/bpf/syscall.c:2348
 __sys_bpf+0x4c2/0x670 kernel/bpf/syscall.c:4651
 __do_sys_bpf kernel/bpf/syscall.c:4755 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4753 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4753
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x94/0x280 mm/page_alloc.c:3396
 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
 ____kasan_kmalloc mm/kasan/common.c:479 [inline]
 __kasan_krealloc+0xa7/0x1b0 mm/kasan/common.c:581
 kasan_krealloc include/linux/kasan.h:284 [inline]
 __do_krealloc mm/slab_common.c:1240 [inline]
 krealloc+0xb1/0xf0 mm/slab_common.c:1277
 push_jmp_history kernel/bpf/verifier.c:2125 [inline]
 is_state_visited kernel/bpf/verifier.c:11061 [inline]
 do_check+0x2d3d/0xeac0 kernel/bpf/verifier.c:11201
 do_check_common+0xe67/0x16c0 kernel/bpf/verifier.c:13485
 do_check_main kernel/bpf/verifier.c:13548 [inline]
 bpf_check+0x31f3/0xf090 kernel/bpf/verifier.c:14119
 bpf_prog_load+0x1043/0x1550 kernel/bpf/syscall.c:2348
 __sys_bpf+0x4c2/0x670 kernel/bpf/syscall.c:4651
 __do_sys_bpf kernel/bpf/syscall.c:4755 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4753 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4753
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff8880637e3c80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
 ffff8880637e3d00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880637e3d80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                        ^
 ffff8880637e3e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880637e3e80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
==================================================================