kvm: failed to shrink bus, removing it completely
==================================================================
BUG: KASAN: use-after-free in kvm_vm_ioctl_unregister_coalesced_mmio+0x217/0x280 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:178
Read of size 8 at addr ffff8880a97c5500 by task syz-executor.5/27885

CPU: 1 PID: 27885 Comm: syz-executor.5 Not tainted 4.14.228-syzkaller #0
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+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 kvm_vm_ioctl_unregister_coalesced_mmio+0x217/0x280 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:178
 kvm_vm_ioctl+0x601/0x13e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3095
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x466459
RSP: 002b:00007faf59f95188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0000000020000240 RSI: 000000004010ae68 RDI: 0000000000000004
RBP: 00007faf59f951d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffcbaeebc9f R14: 00007faf59f95300 R15: 0000000000022000

Allocated by task 27885:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x131/0x3d0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 kvm_vm_ioctl_register_coalesced_mmio+0x51/0x330 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:146
 kvm_vm_ioctl+0xa81/0x13e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3086
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 27885:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 kvm_iodevice_destructor include/kvm/iodev.h:73 [inline]
 kvm_io_bus_unregister_dev.cold+0xd8/0xf8 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3718
 kvm_vm_ioctl_unregister_coalesced_mmio+0x17d/0x280 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:180
 kvm_vm_ioctl+0x601/0x13e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3095
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff8880a97c5500
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes inside of
 64-byte region [ffff8880a97c5500, ffff8880a97c5540)
The buggy address belongs to the page:
page:ffffea0002a5f140 count:1 mapcount:0 mapping:ffff8880a97c5000 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880a97c5000 0000000000000000 0000000100000020
raw: ffffea0002681d20 ffffea00026229e0 ffff88813fe80340 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a97c5400: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880a97c5480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8880a97c5500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff8880a97c5580: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a97c5600: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================
FAULT_INJECTION: forcing a failure.
name fail_page_alloc, interval 1, probability 0, space 0, times 0
dccp_close: ABORT with 481 bytes unread
CPU: 1 PID: 27944 Comm: syz-executor.1 Tainted: G    B           4.14.228-syzkaller #0
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+0x1b2/0x281 lib/dump_stack.c:58
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold+0x10a/0x149 lib/fault-inject.c:149
 should_fail_alloc_page mm/page_alloc.c:2898 [inline]
 prepare_alloc_pages mm/page_alloc.c:4131 [inline]
 __alloc_pages_nodemask+0x22c/0x2720 mm/page_alloc.c:4179
 alloc_pages_current+0x155/0x260 mm/mempolicy.c:2113
 alloc_pages include/linux/gfp.h:520 [inline]
 skb_page_frag_refill+0x1bf/0x490 net/core/sock.c:2206
 tun_build_skb drivers/net/tun.c:1296 [inline]
 tun_get_user+0x1ab3/0x43f0 drivers/net/tun.c:1468
 tun_chr_write_iter+0xe8/0x1e0 drivers/net/tun.c:1612
 call_write_iter include/linux/fs.h:1778 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x44c/0x630 fs/read_write.c:482
 vfs_write+0x17f/0x4d0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xf2/0x210 fs/read_write.c:582
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x41913f
RSP: 002b:00007f19a2976150 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 000000000041913f
RDX: 0000000000000076 RSI: 0000000020000740 RDI: 00000000000000f0
RBP: 00007f19a29761d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007ffe8764631f R14: 00007f19a2976300 R15: 0000000000022000