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BUG: KASAN: use-after-free in __wake_up_common+0x670/0x780 kernel/sched/wait.c:90
Read of size 8 at addr ffff8801c93a64a0 by task syzkaller237854/3772

CPU: 1 PID: 3772 Comm: syzkaller237854 Not tainted 4.15.0-rc8-next-20180119+ #102
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23b/0x360 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 __wake_up_common+0x670/0x780 kernel/sched/wait.c:90
 __wake_up_common_lock+0x1b4/0x310 kernel/sched/wait.c:125
 __wake_up+0xe/0x10 kernel/sched/wait.c:149
 eventfd_release+0x4a/0x60 fs/eventfd.c:112
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:869
 do_group_exit+0x149/0x400 kernel/exit.c:972
 get_signal+0x73a/0x16d0 kernel/signal.c:2346
 do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:161
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x9e/0xa0
RIP: 0033:0x445d89
RSP: 002b:00007efca4510da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00000000006dbc24 RCX: 0000000000445d89
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dbc24
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc20
R13: 6f68762f7665642f R14: 00007efca45119c0 R15: 0000000000000007

Allocated by task 3772:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
 __do_kmalloc_node mm/slab.c:3669 [inline]
 __kmalloc_node+0x47/0x70 mm/slab.c:3676
 kmalloc_node include/linux/slab.h:554 [inline]
 kvmalloc_node+0x64/0xd0 mm/util.c:397
 kvmalloc include/linux/mm.h:541 [inline]
 vhost_net_open+0x27/0x670 drivers/vhost/net.c:921
 misc_open+0x382/0x500 drivers/char/misc.c:154
 chrdev_open+0x257/0x730 fs/char_dev.c:417
 do_dentry_open+0x667/0xd40 fs/open.c:752
 vfs_open+0x107/0x220 fs/open.c:866
 do_last fs/namei.c:3397 [inline]
 path_openat+0x1151/0x3530 fs/namei.c:3537
 do_filp_open+0x25b/0x3b0 fs/namei.c:3572
 do_sys_open+0x502/0x6d0 fs/open.c:1059
 SYSC_openat fs/open.c:1086 [inline]
 SyS_openat+0x30/0x40 fs/open.c:1080
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 3772:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xd9/0x260 mm/slab.c:3800
 kvfree+0x36/0x60 mm/util.c:416
 vhost_net_release+0x159/0x190 drivers/vhost/net.c:1031
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:869
 do_group_exit+0x149/0x400 kernel/exit.c:972
 get_signal+0x73a/0x16d0 kernel/signal.c:2346
 do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:161
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x9e/0xa0

The buggy address belongs to the object at ffff8801c93a1bc0
 which belongs to the cache kmalloc-65536 of size 65536
The buggy address is located 18656 bytes inside of
 65536-byte region [ffff8801c93a1bc0, ffff8801c93b1bc0)
The buggy address belongs to the page:
page:ffffea000724e800 count:1 mapcount:0 mapping:ffff8801c93a1bc0 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801c93a1bc0 0000000000000000 0000000100000001
raw: ffffea000724e020 ffffea0006fe3020 ffff8801dac02500 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c93a6380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c93a6400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801c93a6480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff8801c93a6500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c93a6580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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