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BUG: KASAN: use-after-free in atomic64_read include/asm-generic/atomic-instrumented.h:27 [inline]
BUG: KASAN: use-after-free in atomic_long_read include/asm-generic/atomic-long.h:47 [inline]
BUG: KASAN: use-after-free in __mutex_trylock_or_owner kernel/locking/mutex.c:84 [inline]
BUG: KASAN: use-after-free in __mutex_trylock kernel/locking/mutex.c:125 [inline]
BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:759 [inline]
BUG: KASAN: use-after-free in __mutex_lock+0x193/0x1820 kernel/locking/mutex.c:894
Read of size 8 at addr ffff8801c98452f8 by task kworker/0:3/4827

CPU: 0 PID: 4827 Comm: kworker/0:3 Not tainted 4.18.0-rc7+ #174
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events p9_poll_workfn
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 atomic64_read include/asm-generic/atomic-instrumented.h:27 [inline]
 atomic_long_read include/asm-generic/atomic-long.h:47 [inline]
 __mutex_trylock_or_owner kernel/locking/mutex.c:84 [inline]
 __mutex_trylock kernel/locking/mutex.c:125 [inline]
 __mutex_lock_common kernel/locking/mutex.c:759 [inline]
 __mutex_lock+0x193/0x1820 kernel/locking/mutex.c:894
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:909
 ep_scan_ready_list+0xb77/0xf50 fs/eventpoll.c:681
 ep_eventpoll_poll+0x192/0x200 fs/eventpoll.c:937
 vfs_poll include/linux/poll.h:86 [inline]
 p9_fd_poll+0x1ce/0x2b0 net/9p/trans_fd.c:248
 p9_poll_mux net/9p/trans_fd.c:617 [inline]
 p9_poll_workfn+0x463/0x6d0 net/9p/trans_fd.c:1107
 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

Allocated by task 23384:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
 kmalloc include/linux/slab.h:513 [inline]
 kzalloc include/linux/slab.h:707 [inline]
 ep_alloc fs/eventpoll.c:1016 [inline]
 do_epoll_create+0x170/0x5c0 fs/eventpoll.c:1952
 __do_sys_epoll_create1 fs/eventpoll.c:1983 [inline]
 __se_sys_epoll_create1 fs/eventpoll.c:1981 [inline]
 __x64_sys_epoll_create1+0x31/0x40 fs/eventpoll.c:1981
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 23335:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x260 mm/slab.c:3813
 ep_free+0x273/0x310 fs/eventpoll.c:856
 ep_eventpoll_release+0x44/0x60 fs/eventpoll.c:864
 __fput+0x355/0x8b0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 get_signal+0x1559/0x1970 kernel/signal.c:2298
 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop+0x2e0/0x370 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801c98452c0
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 56 bytes inside of
 512-byte region [ffff8801c98452c0, ffff8801c98454c0)
The buggy address belongs to the page:
page:ffffea0007261140 count:1 mapcount:0 mapping:ffff8801dac00940 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea00075fe0c8 ffffea0007336d48 ffff8801dac00940
raw: 0000000000000000 ffff8801c9845040 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c9845180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c9845200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8801c9845280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                                ^
 ffff8801c9845300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c9845380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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