syzbot

audit: type=1400 audit(1517473721.224:7): avc:  denied  { map } for  pid=4106 comm="syzkaller760230" path="/root/syzkaller760230170" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
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BUG: KASAN: use-after-free in __lock_acquire+0x3d4d/0x3e00 kernel/locking/lockdep.c:3310
Read of size 8 at addr ffff8801bde848f0 by task syzkaller760230/4106

CPU: 1 PID: 4106 Comm: syzkaller760230 Not tainted 4.15.0+ #290
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:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 __lock_acquire+0x3d4d/0x3e00 kernel/locking/lockdep.c:3310
 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x96/0xc0 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
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:865
 do_group_exit+0x149/0x400 kernel/exit.c:968
 SYSC_exit_group kernel/exit.c:979 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:977
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x4429f8
RSP: 002b:00007fff89cbcc28 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 00000000004429f8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000006ce018 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a40
R13: 0000000000401ad0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4106:
 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:551
 kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3606
 kmalloc include/linux/slab.h:499 [inline]
 kzalloc include/linux/slab.h:688 [inline]
 binder_get_thread+0x1cf/0x870 drivers/android/binder.c:4219
 binder_poll+0x8c/0x390 drivers/android/binder.c:4321
 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 4106:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3484 [inline]
 kfree+0xd6/0x260 mm/slab.c:3799
 binder_free_thread drivers/android/binder.c:4246 [inline]
 binder_thread_dec_tmpref+0x27f/0x310 drivers/android/binder.c:1821
 binder_thread_release+0x27d/0x540 drivers/android/binder.c:4310
 binder_ioctl+0xc02/0x1417 drivers/android/binder.c:4527
 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 ffff8801bde84840
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 176 bytes inside of
 512-byte region [ffff8801bde84840, ffff8801bde84a40)
The buggy address belongs to the page:
page:ffffea0006f7a100 count:1 mapcount:0 mapping:ffff8801bde840c0 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801bde840c0 0000000000000000 0000000100000006
raw: ffffea0006f7b620 ffff8801db001748 ffff8801db000940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801bde84780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801bde84800: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8801bde84880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff8801bde84900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801bde84980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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