------------[ cut here ]------------ WARNING: ./include/linux/ns_common.h:255 at __ns_ref_put include/linux/ns_common.h:255 [inline], CPU#0: syz-executor/6822 WARNING: ./include/linux/ns_common.h:255 at put_user_ns include/linux/user_namespace.h:189 [inline], CPU#0: syz-executor/6822 WARNING: ./include/linux/ns_common.h:255 at put_cred_rcu+0x2c5/0x340 kernel/cred.c:61, CPU#0: syz-executor/6822 Modules linked in: CPU: 0 UID: 0 PID: 6822 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:__ns_ref_put include/linux/ns_common.h:255 [inline] RIP: 0010:put_user_ns include/linux/user_namespace.h:189 [inline] RIP: 0010:put_cred_rcu+0x2c5/0x340 kernel/cred.c:61 Code: 5c 41 5d 41 5e 41 5f 5d e9 78 c4 8d 00 e8 83 a5 32 00 4c 89 e7 be 03 00 00 00 e8 f6 52 0a 03 e9 b8 fe ff ff e8 6c a5 32 00 90 <0f> 0b 90 eb 9f e8 61 a5 32 00 4c 89 ff be 03 00 00 00 e8 d4 52 0a RSP: 0018:ffffc90000007ba8 EFLAGS: 00010246 RAX: ffffffff818f2934 RBX: ffff88802a2e9aa0 RCX: ffff8880274b1e80 RDX: 0000000000000100 RSI: 0000000000000004 RDI: 0000000000000000 RBP: 0000000000000004 R08: ffff8880303245bb R09: 1ffff110060648b7 R10: dffffc0000000000 R11: ffffed10060648b8 R12: dffffc0000000000 R13: ffff88802a2e9a00 R14: ffff888030324428 R15: ffff8880303245b8 FS: 000055556abcf500(0000) GS:ffff888125a7c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe6f2f4e38 CR3: 000000002ef48000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 000000000000000c DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: rcu_do_batch kernel/rcu/tree.c:2605 [inline] rcu_core+0xcab/0x1770 kernel/rcu/tree.c:2861 handle_softirqs+0x286/0x870 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:727 irq_exit_rcu+0x9/0x30 kernel/softirq.c:743 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:56 [inline] RIP: 0010:unwind_next_frame+0x183c/0x2390 arch/x86/kernel/unwind_orc.c:665 Code: 00 4d 8b 66 38 49 8d 7e 08 48 89 f8 48 c1 e8 03 80 3c 28 00 74 05 e8 73 af b3 00 4d 8b 6e 08 4d 8d 7e 10 4c 89 f8 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 ff e8 56 af b3 00 49 8b 07 4d 39 e5 0f 96 RSP: 0018:ffffc90003f7f678 EFLAGS: 00000a06 RAX: 1ffff920007efeeb RBX: ffffffff907e7e01 RCX: 0000000000000001 RDX: ffffc90003f7f788 RSI: dffffc0000000000 RDI: ffffc90003f7f750 RBP: dffffc0000000000 R08: ffffc90003f7fe98 R09: 0000000000000000 R10: ffffc90003f7f798 R11: fffff520007efef5 R12: ffffc90003f7fea8 R13: ffffc90003f78000 R14: ffffc90003f7f748 R15: ffffc90003f7f758 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2547 [inline] slab_free mm/slub.c:6642 [inline] kfree+0x19a/0x6d0 mm/slub.c:6849 tomoyo_realpath_from_path+0x598/0x5d0 security/tomoyo/realpath.c:286 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_number_perm+0x1e8/0x5a0 security/tomoyo/file.c:723 security_file_ioctl+0xcb/0x2d0 security/security.c:2435 __do_sys_ioctl fs/ioctl.c:591 [inline] __se_sys_ioctl+0x47/0x170 fs/ioctl.c:583 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: 0033:0x7fba8b58f2cb Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00 RSP: 002b:00007ffe6f2f6680 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fba8b58f2cb RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000003 RBP: 00007ffe6f2f671c R08: 0000000000000000 R09: 00007ffe6f2f6427 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000254 R13: 00000000000927c0 R14: 000000000007fc1b R15: 00007ffe6f2f6770 ---------------- Code disassembly (best guess): 0: 00 4d 8b add %cl,-0x75(%rbp) 3: 66 38 49 8d data16 cmp %cl,-0x73(%rcx) 7: 7e 08 jle 0x11 9: 48 89 f8 mov %rdi,%rax c: 48 c1 e8 03 shr $0x3,%rax 10: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) 14: 74 05 je 0x1b 16: e8 73 af b3 00 call 0xb3af8e 1b: 4d 8b 6e 08 mov 0x8(%r14),%r13 1f: 4d 8d 7e 10 lea 0x10(%r14),%r15 23: 4c 89 f8 mov %r15,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) <-- trapping instruction 2e: 74 08 je 0x38 30: 4c 89 ff mov %r15,%rdi 33: e8 56 af b3 00 call 0xb3af8e 38: 49 8b 07 mov (%r15),%rax 3b: 4d 39 e5 cmp %r12,%r13 3e: 0f .byte 0xf 3f: 96 xchg %eax,%esi