------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 25352 at lib/refcount.c:25 refcount_warn_saturate+0xfa/0x1d0
Modules linked in:
CPU: 0 UID: 0 PID: 25352 Comm: syz.0.4757 Not tainted 6.16.0-rc6-syzkaller-00128-g81e0db8e8398-dirty #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:refcount_warn_saturate+0xfa/0x1d0
Code: 00 00 e8 09 d6 ff fc 5b 41 5e c3 cc cc cc cc cc e8 fb d5 ff fc c6 05 62 74 cb 0a 01 90 48 c7 c7 80 41 e2 8b e8 37 c3 c3 fc 90 <0f> 0b 90 90 eb d7 e8 db d5 ff fc c6 05 43 74 cb 0a 01 90 48 c7 c7
RSP: 0018:ffffc90004ccfd48 EFLAGS: 00010246
RAX: aef2f3d0b3ba5000 RBX: 0000000000000002 RCX: ffff8881314a5640
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc90004ccfe48 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfaa6c R12: 1ffff11008238a05
R13: 1ffff92000999fb4 R14: ffff888027743ec8 R15: dffffc0000000000
FS:  00007f09c6d426c0(0000) GS:ffff8880b8623000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055555fe62808 CR3: 0000000112f1c000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 ax25_setsockopt+0xabb/0xc20
 do_sock_setsockopt+0x17c/0x1b0
 __x64_sys_setsockopt+0x13f/0x1b0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f09c5f8e9a9
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:00007f09c6d42038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f09c61b5fa0 RCX: 00007f09c5f8e9a9
RDX: 0000000000000019 RSI: 0000000000000101 RDI: 0000000000000009
RBP: 00007f09c6010d69 R08: 0000000000000010 R09: 0000000000000000
R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f09c61b5fa0 R15: 00007fffd994e138
 </TASK>
