------------[ 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.3.4062/25743 Modules linked in: CPU: 1 UID: 0 PID: 25743 Comm: syz.3.4062 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25 Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 7b 40 1e fd 48 8d 3d 54 64 75 0b 67 48 0f b9 3a eb 4a e8 68 40 1e fd 48 8d 3d 51 64 75 0b <67> 48 0f b9 3a eb 37 e8 55 40 1e fd 48 8d 3d 4e 64 75 0b 67 48 0f RSP: 0018:ffffc900038bf380 EFLAGS: 00010287 RAX: ffffffff84a672b8 RBX: 0000000000000002 RCX: 0000000000080000 RDX: ffffc90014b7d000 RSI: 000000000000c7fe RDI: ffffffff901bd710 RBP: 0000000000000000 R08: ffff888030b6bc80 R09: 0000000000000005 R10: 0000000000000004 R11: 0000000000000002 R12: ffff888042810854 R13: 1ffff920007e1a0c R14: ffff888033c3a658 R15: ffff888033c3a600 FS: 00007f45bb5096c0(0000) GS:ffff888125596000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b3241bffc CR3: 000000009a7a2000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: __add_used_btf+0x152/0x2e0 kernel/bpf/verifier.c:21307 check_pseudo_btf_id+0x764/0xbb0 kernel/bpf/verifier.c:21438 resolve_pseudo_ldimm64+0x3f4/0xc90 kernel/bpf/verifier.c:21675 bpf_check+0x1d82/0x1ce00 kernel/bpf/verifier.c:25901 bpf_prog_load+0x1484/0x1ae0 kernel/bpf/syscall.c:3089 __sys_bpf+0x618/0x950 kernel/bpf/syscall.c:6229 __do_sys_bpf kernel/bpf/syscall.c:6342 [inline] __se_sys_bpf kernel/bpf/syscall.c:6340 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6340 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: 0033:0x7f45ba59bf79 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:00007f45bb509028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f45ba815fa0 RCX: 00007f45ba59bf79 RDX: 0000000000000094 RSI: 0000200000000180 RDI: 0000000000000005 RBP: 00007f45ba6327e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f45ba816038 R14: 00007f45ba815fa0 R15: 00007ffdf9a619b8 ---------------- 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 7b 40 1e fd call 0xfd1e408b 10: 48 8d 3d 54 64 75 0b lea 0xb756454(%rip),%rdi # 0xb75646b 17: 67 48 0f b9 3a ud1 (%edx),%rdi 1c: eb 4a jmp 0x68 1e: e8 68 40 1e fd call 0xfd1e408b 23: 48 8d 3d 51 64 75 0b lea 0xb756451(%rip),%rdi # 0xb75647b * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: eb 37 jmp 0x68 31: e8 55 40 1e fd call 0xfd1e408b 36: 48 8d 3d 4e 64 75 0b lea 0xb75644e(%rip),%rdi # 0xb75648b 3d: 67 addr32 3e: 48 rex.W 3f: 0f .byte 0xf