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BUG: KASAN: use-after-free in debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline]
BUG: KASAN: use-after-free in do_raw_spin_lock+0x1e0/0x220 kernel/locking/spinlock_debug.c:112
Read of size 4 at addr ffff8801cff8caa4 by task syz-executor7/13326

CPU: 1 PID: 13326 Comm: syz-executor7 Not tainted 4.15.0-rc8-next-20180118+ #100
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_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline]
 do_raw_spin_lock+0x1e0/0x220 kernel/locking/spinlock_debug.c:112
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:117 [inline]
 _raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:152
 remove_wait_queue+0x81/0x350 kernel/sched/wait.c:50
 ep_remove_wait_queue fs/eventpoll.c:595 [inline]
 ep_unregister_pollwait.isra.7+0x18c/0x590 fs/eventpoll.c:613
 ep_free+0x13f/0x320 fs/eventpoll.c:830
 ep_eventpoll_release+0x44/0x60 fs/eventpoll.c:862
 __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
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:165
 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: 0033:0x452e99
RSP: 002b:00007f08069f8c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000124
RAX: 0000000000000018 RBX: 000000000071bf58 RCX: 0000000000452e99
RDX: 0000000000000000 RSI: 0000000000000018 RDI: 0000000000000016
RBP: 0000000000000066 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006eea30
R13: 00000000ffffffff R14: 00007f08069f96d4 R15: 0000000000000002

Allocated by task 13317:
 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
 kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3607
 kmalloc include/linux/slab.h:512 [inline]
 kzalloc include/linux/slab.h:701 [inline]
 binder_get_thread+0x1cf/0x870 drivers/android/binder.c:4279
 binder_poll+0x8c/0x390 drivers/android/binder.c:4393
 ep_item_poll.isra.10+0xf2/0x320 fs/eventpoll.c:885
 ep_insert+0x6a2/0x1ac0 fs/eventpoll.c:1457
 SYSC_epoll_ctl fs/eventpoll.c:2104 [inline]
 SyS_epoll_ctl+0x12bf/0x1a80 fs/eventpoll.c:1990
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 13317:
 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
 binder_free_thread drivers/android/binder.c:4306 [inline]
 binder_thread_dec_tmpref+0x27f/0x310 drivers/android/binder.c:1879
 binder_thread_release+0x4a1/0x6b0 drivers/android/binder.c:4382
 binder_ioctl+0xc02/0x1417 drivers/android/binder.c:4599
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x29/0xa0

The buggy address belongs to the object at ffff8801cff8ca00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 164 bytes inside of
 512-byte region [ffff8801cff8ca00, ffff8801cff8cc00)
The buggy address belongs to the page:
page:ffffea00073fe300 count:1 mapcount:0 mapping:ffff8801cff8c000 index:0xffff8801cff8cc80
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801cff8c000 ffff8801cff8cc80 0000000100000004
raw: ffffea0007166020 ffffea0007145860 ffff8801dac00940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cff8c980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801cff8ca00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801cff8ca80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff8801cff8cb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801cff8cb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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