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BUG: KASAN: double-free or invalid-free in io_sqe_files_unregister+0x20b/0x300 fs/io_uring.c:3185

CPU: 1 PID: 16999 Comm: syz-executor.5 Not tainted 5.4.0-rc6-next-20191108 #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_invalid_free+0x65/0xa0 mm/kasan/report.c:468
 __kasan_slab_free+0x13a/0x150 mm/kasan/common.c:450
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 io_sqe_files_unregister+0x20b/0x300 fs/io_uring.c:3185
 io_ring_ctx_free fs/io_uring.c:3998 [inline]
 io_ring_ctx_wait_and_kill+0x348/0x700 fs/io_uring.c:4060
 io_uring_release+0x42/0x50 fs/io_uring.c:4068
 __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:163
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413db1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffe7f823c30 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000413db1
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000001 R08: 0000000061768454 R09: 0000000061768458
R10: 00007ffe7f823d10 R11: 0000000000000293 R12: 000000000075c9a0
R13: 000000000075c9a0 R14: 0000000000760ec8 R15: 000000000075bf2c

Allocated by task 17002:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:510 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x163/0x770 mm/slab.c:3665
 kmalloc_array include/linux/slab.h:598 [inline]
 kcalloc include/linux/slab.h:609 [inline]
 io_sqe_files_register fs/io_uring.c:3373 [inline]
 __io_uring_register+0x11d4/0x3120 fs/io_uring.c:4474
 __do_sys_io_uring_register fs/io_uring.c:4526 [inline]
 __se_sys_io_uring_register fs/io_uring.c:4508 [inline]
 __x64_sys_io_uring_register+0x1a1/0x570 fs/io_uring.c:4508
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 17002:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 io_sqe_files_register fs/io_uring.c:3379 [inline]
 __io_uring_register+0x13a7/0x3120 fs/io_uring.c:4474
 __do_sys_io_uring_register fs/io_uring.c:4526 [inline]
 __se_sys_io_uring_register fs/io_uring.c:4508 [inline]
 __x64_sys_io_uring_register+0x1a1/0x570 fs/io_uring.c:4508
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a1d4c200
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8880a1d4c200, ffff8880a1d4c220)
The buggy address belongs to the page:
page:ffffea0002875300 refcount:1 mapcount:0 mapping:ffff8880aa4001c0 index:0xffff8880a1d4cfc1
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0002908488 ffffea0002643e48 ffff8880aa4001c0
raw: ffff8880a1d4cfc1 ffff8880a1d4c000 000000010000001b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a1d4c100: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a1d4c180: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8880a1d4c200: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
                   ^
 ffff8880a1d4c280: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a1d4c300: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
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