------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 1 PID: 8090 at lib/refcount.c:25 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25 Modules linked in: CPU: 1 UID: 0 PID: 8090 Comm: syz.4.502 Not tainted 6.16.0-rc6-syzkaller-01576-g4701ee5044fb #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25 Code: 00 00 e8 89 d7 ff fc 5b 41 5e e9 d1 30 b2 06 cc e8 7b d7 ff fc c6 05 19 c2 cb 0a 01 90 48 c7 c7 c0 41 e2 8b e8 57 c3 c3 fc 90 <0f> 0b 90 90 eb d7 e8 5b d7 ff fc c6 05 fa c1 cb 0a 01 90 48 c7 c7 RSP: 0000:ffffc900030d7d48 EFLAGS: 00010246 RAX: 304c9212b76dd100 RBX: 0000000000000002 RCX: 0000000000080000 RDX: ffffc9000e0f0000 RSI: 00000000000029ab RDI: 00000000000029ac RBP: ffffc900030d7e48 R08: ffff8880b8624293 R09: 1ffff110170c4852 R10: dffffc0000000000 R11: ffffed10170c4853 R12: 1ffff11006926905 R13: 1ffff9200061afb4 R14: ffff88802f6e1ac8 R15: dffffc0000000000 FS: 00007fccc99d76c0(0000) GS:ffff888125d16000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000317ee000 CR4: 00000000003526f0 Call Trace: ax25_setsockopt+0xabb/0xc20 net/ax25/af_ax25.c:705 do_sock_setsockopt+0x179/0x1b0 net/socket.c:2344 __sys_setsockopt net/socket.c:2369 [inline] __do_sys_setsockopt net/socket.c:2375 [inline] __se_sys_setsockopt net/socket.c:2372 [inline] __x64_sys_setsockopt+0x13f/0x1b0 net/socket.c:2372 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fccc8b8e9a9 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:00007fccc99d7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007fccc8db6080 RCX: 00007fccc8b8e9a9 RDX: 0000000000000019 RSI: 0000000000000101 RDI: 0000000000000009 RBP: 00007fccc8c10d69 R08: 0000000000000010 R09: 0000000000000000 R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fccc8db6080 R15: 00007ffc668551f8