================================================================== BUG: KASAN: use-after-free in percpu_ref_call_confirm_rcu lib/percpu-refcount.c:126 [inline] BUG: KASAN: use-after-free in percpu_ref_switch_to_atomic_rcu+0x3f7/0x400 lib/percpu-refcount.c:165 Read of size 1 at addr ffff8880a8d91830 by task swapper/0/0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.5.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fb/0x318 lib/dump_stack.c:118 print_address_description+0x74/0x5c0 mm/kasan/report.c:374 __kasan_report+0x149/0x1c0 mm/kasan/report.c:506 kasan_report+0x26/0x50 mm/kasan/common.c:641 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:132 percpu_ref_call_confirm_rcu lib/percpu-refcount.c:126 [inline] percpu_ref_switch_to_atomic_rcu+0x3f7/0x400 lib/percpu-refcount.c:165 rcu_do_batch kernel/rcu/tree.c:2186 [inline] rcu_core+0x81b/0x10c0 kernel/rcu/tree.c:2410 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2419 __do_softirq+0x283/0x7bd kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x227/0x230 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x113/0x280 arch/x86/kernel/apic/apic.c:1137 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:61 Code: 89 d9 80 e1 07 80 c1 03 38 c1 7c ba 48 89 df e8 e4 5f 9d f9 eb b0 cc cc 55 48 89 e5 e9 07 00 00 00 0f 00 2d 62 17 4c 00 fb f4 <5d> c3 66 90 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 e9 07 00 00 RSP: 0018:ffffffff89207db8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff1255a25 RBX: ffffffff89275b00 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: ffffffff812c06aa RDI: ffffffff89276344 RBP: ffffffff89207db8 R08: ffffffff89276358 R09: fffffbfff124eb61 R10: fffffbfff124eb61 R11: 0000000000000000 R12: 1ffffffff124eb60 R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffffffff1255a23 arch_safe_halt arch/x86/include/asm/paravirt.h:144 [inline] default_idle+0x50/0x70 arch/x86/kernel/process.c:695 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:686 default_idle_call+0x59/0xa0 kernel/sched/idle.c:94 cpuidle_idle_call kernel/sched/idle.c:154 [inline] do_idle+0x1ec/0x630 kernel/sched/idle.c:269 cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:361 rest_init+0x29d/0x2b0 init/main.c:450 arch_call_rest_init+0xe/0x10 start_kernel+0x676/0x777 init/main.c:784 x86_64_start_reservations+0x18/0x2e arch/x86/kernel/head64.c:490 x86_64_start_kernel+0x7a/0x7d arch/x86/kernel/head64.c:471 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242 Allocated by task 25166: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:515 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 kmem_cache_alloc_trace+0x221/0x2f0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] io_sqe_files_register fs/io_uring.c:5528 [inline] __io_uring_register fs/io_uring.c:6875 [inline] __do_sys_io_uring_register fs/io_uring.c:6955 [inline] __se_sys_io_uring_register+0x1df4/0x3260 fs/io_uring.c:6937 __x64_sys_io_uring_register+0x9b/0xb0 fs/io_uring.c:6937 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 25160: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10d/0x220 mm/slab.c:3757 io_sqe_files_unregister+0x238/0x2b0 fs/io_uring.c:5250 io_ring_ctx_free fs/io_uring.c:6229 [inline] io_ring_ctx_wait_and_kill+0x343d/0x3b00 fs/io_uring.c:6310 io_uring_release+0x5d/0x70 fs/io_uring.c:6318 __fput+0x2e4/0x740 fs/file_table.c:280 ____fput+0x15/0x20 fs/file_table.c:313 task_work_run+0x176/0x1b0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:164 [inline] prepare_exit_to_usermode+0x480/0x5b0 arch/x86/entry/common.c:195 syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:278 do_syscall_64+0x11f/0x1c0 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880a8d91800 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 48 bytes inside of 256-byte region [ffff8880a8d91800, ffff8880a8d91900) The buggy address belongs to the page: page:ffffea0002a36440 refcount:1 mapcount:0 mapping:ffff8880aa4008c0 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea000265d2c8 ffffea00022f7948 ffff8880aa4008c0 raw: 0000000000000000 ffff8880a8d91000 0000000100000008 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a8d91700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a8d91780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880a8d91800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a8d91880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a8d91900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================