------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25, CPU#1: syz.1.450/7825 Modules linked in: CPU: 1 UID: 0 PID: 7825 Comm: syz.1.450 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 RIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25 Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 db 5e 1f fd 48 8d 3d 04 05 76 0b 67 48 0f b9 3a eb 4a e8 c8 5e 1f fd 48 8d 3d 01 05 76 0b <67> 48 0f b9 3a eb 37 e8 b5 5e 1f fd 48 8d 3d fe 04 76 0b 67 48 0f RSP: 0018:ffffc90003f4f380 EFLAGS: 00010287 RAX: ffffffff84a4fb68 RBX: 0000000000000002 RCX: 0000000000080000 RDX: ffffc900044c1000 RSI: 00000000000121d3 RDI: ffffffff901b0070 RBP: 0000000000000000 R08: ffff888034305ac0 R09: 0000000000000005 R10: 0000000000000004 R11: 0000000000000002 R12: ffff888079760854 R13: 1ffff9200160e60c R14: ffff8880118bba58 R15: ffff8880118bba00 FS: 00007f3c0bff66c0(0000) GS:ffff8881255bc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b31f22ff8 CR3: 0000000032ff8000 CR4: 00000000003526f0 DR0: 0000200000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff1 DR7: 0000000000000600 Call Trace: __add_used_btf+0x152/0x2e0 kernel/bpf/verifier.c:21357 check_pseudo_btf_id+0x764/0xbb0 kernel/bpf/verifier.c:21488 resolve_pseudo_ldimm64+0x3f4/0xc90 kernel/bpf/verifier.c:21725 bpf_check+0x1d82/0x1ce00 kernel/bpf/verifier.c:25951 bpf_prog_load+0x1484/0x1ae0 kernel/bpf/syscall.c:3088 __sys_bpf+0x618/0x950 kernel/bpf/syscall.c:6228 __do_sys_bpf kernel/bpf/syscall.c:6341 [inline] __se_sys_bpf kernel/bpf/syscall.c:6339 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6339 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3c0dd9bf79 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3c0bff6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f3c0e015fa0 RCX: 00007f3c0dd9bf79 RDX: 0000000000000094 RSI: 0000200000000180 RDI: 0000000000000005 RBP: 00007f3c0de327e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3c0e016038 R14: 00007f3c0e015fa0 R15: 00007ffc3c211228 ---------------- Code disassembly (best guess): 0: eb 66 jmp 0x68 2: 85 db test %ebx,%ebx 4: 74 3e je 0x44 6: 83 fb 01 cmp $0x1,%ebx 9: 75 4c jne 0x57 b: e8 db 5e 1f fd call 0xfd1f5eeb 10: 48 8d 3d 04 05 76 0b lea 0xb760504(%rip),%rdi # 0xb76051b 17: 67 48 0f b9 3a ud1 (%edx),%rdi 1c: eb 4a jmp 0x68 1e: e8 c8 5e 1f fd call 0xfd1f5eeb 23: 48 8d 3d 01 05 76 0b lea 0xb760501(%rip),%rdi # 0xb76052b * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: eb 37 jmp 0x68 31: e8 b5 5e 1f fd call 0xfd1f5eeb 36: 48 8d 3d fe 04 76 0b lea 0xb7604fe(%rip),%rdi # 0xb76053b 3d: 67 addr32 3e: 48 rex.W 3f: 0f .byte 0xf