syzbot

audit: type=1400 audit(1519800493.311:7): avc:  denied  { map } for  pid=4238 comm="syzkaller305740" path="/root/syzkaller305740266" 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
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3d4d/0x3e00 kernel/locking/lockdep.c:3310
Read of size 8 at addr ffff8801afa039c0 by task syzkaller305740/4238

CPU: 1 PID: 4238 Comm: syzkaller305740 Not tainted 4.16.0-rc3+ #332
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+0x194/0x24d 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
 __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:596 [inline]
 ep_unregister_pollwait.isra.7+0x18c/0x590 fs/eventpoll.c:614
 ep_free+0x13f/0x320 fs/eventpoll.c:832
 ep_eventpoll_release+0x44/0x60 fs/eventpoll.c:864
 __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
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43e958
RSP: 002b:00007ffe63a11468 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043e958
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004be300 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006cc160 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4238:
 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+0x99/0xd0 mm/util.c:419
 kvmalloc include/linux/mm.h:541 [inline]
 kvzalloc include/linux/mm.h:549 [inline]
 alloc_netdev_mqs+0x16d/0xfb0 net/core/dev.c:8299
 ppp_create_interface drivers/net/ppp/ppp_generic.c:3018 [inline]
 ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:866 [inline]
 ppp_ioctl+0x1715/0x2a50 drivers/net/ppp/ppp_generic.c:602
 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
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 4238:
 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:438
 netdev_freemem+0x4c/0x60 net/core/dev.c:8253
 netdev_release+0x10a/0x160 net/core/net-sysfs.c:1502
 device_release+0x7c/0x210 drivers/base/core.c:814
 kobject_cleanup lib/kobject.c:646 [inline]
 kobject_release lib/kobject.c:675 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put+0x14c/0x250 lib/kobject.c:692
 put_device+0x20/0x30 drivers/base/core.c:1931
 free_netdev+0x2f5/0x400 net/core/dev.c:8410
 ppp_destroy_interface+0x2bc/0x390 drivers/net/ppp/ppp_generic.c:3100
 ppp_release+0x12b/0x1a0 drivers/net/ppp/ppp_generic.c:415
 ppp_ioctl+0x3b1/0x2a50 drivers/net/ppp/ppp_generic.c:628
 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
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801afa02e40
 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 2944 bytes inside of
 4096-byte region [ffff8801afa02e40, ffff8801afa03e40)
The buggy address belongs to the page:
page:ffffea0006be8080 count:1 mapcount:0 mapping:ffff8801afa02e40 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801afa02e40 0000000000000000 0000000100000001
raw: ffffea0006bee220 ffffea0006bee7a0 ffff8801dac00dc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801afa03880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801afa03900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801afa03980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff8801afa03a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801afa03a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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