------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 8092 at lib/refcount.c:25 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25 Modules linked in: CPU: 0 UID: 0 PID: 8092 Comm: syz.4.666 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25 Code: 00 00 e8 e9 7a 36 fd 5b 41 5e e9 c1 db bf 06 cc e8 db 7a 36 fd c6 05 cc 7f dd 0a 01 90 48 c7 c7 00 5a be 8b e8 b7 96 f9 fc 90 <0f> 0b 90 90 eb d7 e8 bb 7a 36 fd c6 05 ad 7f dd 0a 01 90 48 c7 c7 RSP: 0018:ffffc9000cc87d28 EFLAGS: 00010246 RAX: 576146e9d92f5b00 RBX: 0000000000000002 RCX: ffff88802b938000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002 RBP: ffffc9000cc87e38 R08: ffff8880b8824293 R09: 1ffff11017104852 R10: dffffc0000000000 R11: ffffed1017104853 R12: 1ffff1100f3fc205 R13: 1ffff92001990fb0 R14: ffff888078b9e4c8 R15: dffffc0000000000 FS: 00007f6dda3a86c0(0000) GS:ffff888126139000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6dda387d58 CR3: 000000007fbb6000 CR4: 00000000003526f0 Call Trace: ax25_setsockopt+0xabb/0xc20 net/ax25/af_ax25.c:705 do_sock_setsockopt+0x17c/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: 0033:0x7f6dd958e9a9 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:00007f6dda3a8038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f6dd97b5fa0 RCX: 00007f6dd958e9a9 RDX: 0000000000000019 RSI: 0000000000000101 RDI: 000000000000000c RBP: 00007f6dd9610d69 R08: 0000000000000010 R09: 0000000000000000 R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f6dd97b5fa0 R15: 00007ffe4c172218