================================================================== 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+0x4a3/0x540 lib/percpu-refcount.c:165 Read of size 1 at addr ffff888075f41230 by task syz-executor.2/29464 CPU: 0 PID: 29464 Comm: syz-executor.2 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+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 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+0x4a3/0x540 lib/percpu-refcount.c:165 rcu_do_batch kernel/rcu/tree.c:2186 [inline] rcu_core+0x5e1/0x1390 kernel/rcu/tree.c:2410 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2419 __do_softirq+0x262/0x98c kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x19b/0x1e0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:set_page_dirty+0x0/0x850 mm/page-writeback.c:2550 Code: 49 89 fc 53 48 89 f3 e8 de 10 df ff 4c 29 e3 b9 ff ff ff ff b8 01 00 00 00 48 0f bd cb d1 f9 5b 48 d3 e0 41 5c 5d c3 0f 1f 00 <55> 48 89 e5 41 57 41 56 41 55 41 54 49 89 fc 53 4d 8d 6c 24 08 48 RSP: 0018:ffffc9000afcf4c8 EFLAGS: 00000212 ORIG_RAX: ffffffffffffff13 RAX: 0000000000040000 RBX: 0000000000000080 RCX: ffffc9000cb9d000 RDX: 0000000000008592 RSI: ffffffff81c96118 RDI: ffffea00023d11c0 RBP: ffffc9000afcf520 R08: ffff8880a6f80380 R09: fffff9400047a239 R10: fffff9400047a238 R11: ffffea00023d11c7 R12: ffffea00023d11c0 R13: 0000000000000010 R14: ffff88808ef3e1d0 R15: ffff88808ef3e180 generic_perform_write+0x2fe/0x540 mm/filemap.c:3298 __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3416 generic_file_write_iter+0x420/0x68e mm/filemap.c:3448 call_write_iter include/linux/fs.h:1901 [inline] do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693 do_iter_write fs/read_write.c:998 [inline] do_iter_write+0x184/0x610 fs/read_write.c:979 vfs_iter_write+0x77/0xb0 fs/read_write.c:1039 iter_file_splice_write+0x717/0xc10 fs/splice.c:760 do_splice_from fs/splice.c:863 [inline] direct_splice_actor+0x123/0x190 fs/splice.c:1037 splice_direct_to_actor+0x3b4/0xa30 fs/splice.c:992 do_splice_direct+0x1da/0x2a0 fs/splice.c:1080 do_sendfile+0x597/0xd00 fs/read_write.c:1520 __do_sys_sendfile64 fs/read_write.c:1581 [inline] __se_sys_sendfile64 fs/read_write.c:1567 [inline] __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1567 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b399 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f0684f24c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f0684f256d4 RCX: 000000000045b399 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000bb1 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000008cb R14: 00000000004ca259 R15: 000000000075bf2c Allocated by task 29459: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:515 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 kmem_cache_alloc_trace+0x158/0x790 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:5564 [inline] __io_uring_register+0xb07/0x2f70 fs/io_uring.c:6996 __do_sys_io_uring_register fs/io_uring.c:7076 [inline] __se_sys_io_uring_register fs/io_uring.c:7058 [inline] __x64_sys_io_uring_register+0x1a1/0x560 fs/io_uring.c:7058 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 29457: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 io_sqe_files_unregister+0x203/0x2f0 fs/io_uring.c:5276 io_ring_ctx_free fs/io_uring.c:6265 [inline] io_ring_ctx_wait_and_kill+0x4ed/0xa60 fs/io_uring.c:6356 io_uring_release+0x42/0x50 fs/io_uring.c:6364 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:278 [inline] do_syscall_64+0x676/0x790 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888075f41200 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 48 bytes inside of 256-byte region [ffff888075f41200, ffff888075f41300) The buggy address belongs to the page: page:ffffea0001d7d040 refcount:1 mapcount:0 mapping:ffff8880aa4008c0 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea0002a0d548 ffffea000263cc08 ffff8880aa4008c0 raw: 0000000000000000 ffff888075f41000 0000000100000008 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888075f41100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888075f41180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888075f41200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888075f41280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888075f41300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================