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 ffff8880a98ecb00 by task syz-executor.3/25808

CPU: 0 PID: 25808 Comm: syz-executor.3 Not tainted 4.14.202-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+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 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:3096
 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: 0033:0x45de59
RSP: 002b:00007f0f84a88c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000000126c0 RCX: 000000000045de59
RDX: 0000000020000180 RSI: 000000004010ae68 RDI: 0000000000000004
RBP: 00007f0f84a88ca0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffdfe4fb38f R14: 00007f0f84a899c0 R15: 000000000118bf2c

Allocated by task 25808:
 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:3087
 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 25808:
 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+0xd8/0x101 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3719
 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:3096
 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 ffff8880a98ecb00
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes inside of
 64-byte region [ffff8880a98ecb00, ffff8880a98ecb40)
The buggy address belongs to the page:
page:ffffea0002a63b00 count:1 mapcount:0 mapping:ffff8880a98ec000 index:0xffff8880a98ecb80
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880a98ec000 ffff8880a98ecb80 000000010000001f
raw: ffffea0002c03e60 ffffea00025ebb20 ffff88813fe80340 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a98eca00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff8880a98eca80: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>ffff8880a98ecb00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff8880a98ecb80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880a98ecc00: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
==================================================================