R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004020e0
R13: 0000000000402170 R14: 0000000000000000 R15: 0000000000000000
kvm: failed to shrink bus, removing it completely
==================================================================
BUG: KASAN: use-after-free in kvm_vm_ioctl_unregister_coalesced_mmio+0x25a/0x2c0 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:178
Read of size 8 at addr ffff88809858b200 by task syz-executor941/8113

CPU: 1 PID: 8113 Comm: syz-executor941 Not tainted 4.19.155-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2fe lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1c7 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
 kvm_vm_ioctl_unregister_coalesced_mmio+0x25a/0x2c0 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:178
 kvm_vm_ioctl+0x532/0x16e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3252
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440879
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc2f0024d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffc2f0024e0 RCX: 0000000000440879
RDX: 0000000020000180 RSI: 000000004010ae68 RDI: 0000000000000004
RBP: 0000000000000005 R08: 0000000000000001 R09: 00007ffc2f000031
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004020e0
R13: 0000000000402170 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 8113:
 kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
 kmalloc include/linux/slab.h:515 [inline]
 kzalloc include/linux/slab.h:709 [inline]
 kvm_vm_ioctl_register_coalesced_mmio+0x51/0x350 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:146
 kvm_vm_ioctl+0xc63/0x16e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3243
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8113:
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcc/0x210 mm/slab.c:3822
 kvm_iodevice_destructor include/kvm/iodev.h:73 [inline]
 kvm_io_bus_unregister_dev.cold+0xf0/0x110 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3875
 kvm_vm_ioctl_unregister_coalesced_mmio+0x1be/0x2c0 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:180
 kvm_vm_ioctl+0x532/0x16e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3252
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809858b200
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes inside of
 64-byte region [ffff88809858b200, ffff88809858b240)
The buggy address belongs to the page:
page:ffffea00026162c0 count:1 mapcount:0 mapping:ffff88813bff0340 index:0xffff88809858bf80
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff88813bff1338 ffffea000261c508 ffff88813bff0340
raw: ffff88809858bf80 ffff88809858b000 000000010000001e 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809858b100: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff88809858b180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88809858b200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff88809858b280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88809858b300: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================