------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 14648 at lib/refcount.c:25 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25
Modules linked in:
CPU: 0 UID: 0 PID: 14648 Comm: syz.1.2479 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25
Code: 00 00 e8 39 51 32 fd 5b 41 5e c3 cc cc cc cc cc e8 2b 51 32 fd c6 05 fc 9e fa 0a 01 90 48 c7 c7 20 8c bf 8b e8 b7 6d f5 fc 90 <0f> 0b 90 90 eb d7 e8 0b 51 32 fd c6 05 dd 9e fa 0a 01 90 48 c7 c7
RSP: 0018:ffffc90003717d28 EFLAGS: 00010246
RAX: 2985be25ccd47200 RBX: 0000000000000002 RCX: ffff88807d7e9e40
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc90003717e38 R08: ffffc90003717a47 R09: 1ffff920006e2f48
R10: dffffc0000000000 R11: fffff520006e2f49 R12: 1ffff1100df42b05
R13: 1ffff920006e2fb0 R14: ffff88807ba1cac8 R15: dffffc0000000000
FS:  00007f2eb5a056c0(0000) GS:ffff888125d3b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2eb59c3d58 CR3: 00000000328a6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ax25_setsockopt+0xabb/0xc20 net/ax25/af_ax25.c:705
 do_sock_setsockopt+0x179/0x1b0 net/socket.c:2360
 __sys_setsockopt net/socket.c:2385 [inline]
 __do_sys_setsockopt net/socket.c:2391 [inline]
 __se_sys_setsockopt net/socket.c:2388 [inline]
 __x64_sys_setsockopt+0x13f/0x1b0 net/socket.c:2388
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2eb4b8eec9
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:00007f2eb5a05038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f2eb4de5fa0 RCX: 00007f2eb4b8eec9
RDX: 0000000000000019 RSI: 0000000000000101 RDI: 0000000000000009
RBP: 00007f2eb4c11f91 R08: 0000000000000010 R09: 0000000000000000
R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2eb4de6038 R14: 00007f2eb4de5fa0 R15: 00007ffd75233bc8
 </TASK>