------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 7759 at lib/refcount.c:25 refcount_warn_saturate+0x13a/0x1d0 lib/refcount.c:25
Modules linked in:
CPU: 1 UID: 0 PID: 7759 Comm: syz-executor156 Not tainted 6.15.0-rc1-syzkaller-00209-gfaeefc173be4 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:refcount_warn_saturate+0x13a/0x1d0 lib/refcount.c:25
Code: 00 6b a1 8c e8 17 87 7d fc 90 0f 0b 90 90 eb b9 e8 0b 65 be fc c6 05 94 dc 44 0b 01 90 48 c7 c7 60 6b a1 8c e8 f7 86 7d fc 90 <0f> 0b 90 90 eb 99 e8 eb 64 be fc c6 05 75 dc 44 0b 01 90 48 c7 c7
RSP: 0018:ffffc9000c387c68 EFLAGS: 00010246
RAX: 113b5cde664dc600 RBX: ffff88802dd75ac8 RCX: ffff8880280d3c00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000002 R08: ffffffff81828a12 R09: fffffbfff1d7a978
R10: dffffc0000000000 R11: fffffbfff1d7a978 R12: 1ffff11005877705
R13: ffff88802dd75a00 R14: ffff888035a16000 R15: ffff88802c3bb828
FS:  0000555555edd380(0000) GS:ffff888125093000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000025eea000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ax25_setsockopt+0xbb7/0xf00 net/ax25/af_ax25.c:705
 do_sock_setsockopt+0x3b1/0x710 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+0x1ee/0x280 net/socket.c:2324
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3eac8e88a9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 1a 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd0a65d538 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007f3eac8e88a9
RDX: 0000000000000019 RSI: 0000000000000101 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000010 R09: 00007f3eac936214
R10: 0000200000000000 R11: 0000000000000246 R12: 00007ffd0a65d55c
R13: 00007ffd0a65d590 R14: 00007ffd0a65d570 R15: 000000000000016d
 </TASK>