------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 24330 at lib/refcount.c:25 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25
Modules linked in:
CPU: 0 UID: 0 PID: 24330 Comm: syz.2.8097 Not tainted 6.15.0-rc3-syzkaller-00584-gcc17b4b9c332 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25
Code: 00 00 e8 e9 b7 07 fd 5b 41 5e c3 cc cc cc cc cc e8 db b7 07 fd c6 05 b0 14 b1 0a 01 90 48 c7 c7 e0 7e c1 8b e8 c7 16 cc fc 90 <0f> 0b 90 90 eb d7 e8 bb b7 07 fd c6 05 91 14 b1 0a 01 90 48 c7 c7
RSP: 0018:ffffc9000dd97c88 EFLAGS: 00010246
RAX: 6475ee6f5fc26700 RBX: 0000000000000002 RCX: ffff888025511e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc9000dd97d90 R08: ffff8880b8923e93 R09: 1ffff110171247d2
R10: dffffc0000000000 R11: ffffed10171247d3 R12: 1ffff1100c016205
R13: 1ffff92001bb2f9c R14: ffff888064e87ac8 R15: dffffc0000000000
FS:  00007f53978ce6c0(0000) GS:ffff8881260c4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000007f6ec000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ax25_setsockopt+0xabb/0xc20 net/ax25/af_ax25.c:705
 do_sock_setsockopt+0x257/0x3e0 net/socket.c:2296
 __sys_setsockopt net/socket.c:2321 [inline]
 __do_sys_setsockopt net/socket.c:2327 [inline]
 __se_sys_setsockopt net/socket.c:2324 [inline]
 __x64_sys_setsockopt+0x18b/0x220 net/socket.c:2324
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f539698d169
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:00007f53978ce038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f5396ba5fa0 RCX: 00007f539698d169
RDX: 0000000000000019 RSI: 0000000000000101 RDI: 0000000000000004
RBP: 00007f5396a0e990 R08: 0000000000000010 R09: 0000000000000000
R10: 0000200000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5396ba5fa0 R15: 00007fff27b43678
 </TASK>