kvm: failed to shrink bus, removing it completely
==================================================================
BUG: KASAN: use-after-free in kvm_vm_ioctl_unregister_coalesced_mmio+0xe6/0x3a0 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:187
Read of size 8 at addr ffff8881eaea1e80 by task syz-executor.4/27348

CPU: 1 PID: 27348 Comm: syz-executor.4 Not tainted 5.4.96-syzkaller-00126-g72d1876a39cf #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+0x1d8/0x24e lib/dump_stack.c:118
 print_address_description+0x9b/0x650 mm/kasan/report.c:374
 __kasan_report+0x182/0x1f0 mm/kasan/report.c:506
 kasan_report+0x30/0x60 mm/kasan/common.c:634
 kvm_vm_ioctl_unregister_coalesced_mmio+0xe6/0x3a0 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:187
 kvm_vm_ioctl+0x947/0x1a40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3419
 do_vfs_ioctl+0x76a/0x1720 fs/ioctl.c:47
 ksys_ioctl fs/ioctl.c:742 [inline]
 __do_sys_ioctl fs/ioctl.c:749 [inline]
 __se_sys_ioctl fs/ioctl.c:747 [inline]
 __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747
 do_syscall_64+0xcb/0x150 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x465b09
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f645d81a188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465b09
RDX: 00000000200000c0 RSI: 000000004010ae68 RDI: 0000000000000004
RBP: 00007f645d81a1d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc3680c63f R14: 00007f645d81a300 R15: 0000000000022000

Allocated by task 27348:
 save_stack mm/kasan/common.c:69 [inline]
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc+0x137/0x1e0 mm/kasan/common.c:510
 kmem_cache_alloc_trace+0x139/0x2b0 mm/slub.c:2830
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:690 [inline]
 kvm_vm_ioctl_register_coalesced_mmio+0x86/0x310 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:150
 kvm_vm_ioctl+0x7f2/0x1a40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3410
 do_vfs_ioctl+0x76a/0x1720 fs/ioctl.c:47
 ksys_ioctl fs/ioctl.c:742 [inline]
 __do_sys_ioctl fs/ioctl.c:749 [inline]
 __se_sys_ioctl fs/ioctl.c:747 [inline]
 __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747
 do_syscall_64+0xcb/0x150 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 27348:
 save_stack mm/kasan/common.c:69 [inline]
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x18a/0x240 mm/kasan/common.c:471
 slab_free_hook mm/slub.c:1453 [inline]
 slab_free_freelist_hook+0x7b/0x150 mm/slub.c:1486
 slab_free mm/slub.c:3051 [inline]
 kfree+0xe0/0x660 mm/slub.c:4017
 kvm_iodevice_destructor include/kvm/iodev.h:61 [inline]
 kvm_io_bus_unregister_dev+0x377/0x470 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4041
 kvm_vm_ioctl_unregister_coalesced_mmio+0x268/0x3a0 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:190
 kvm_vm_ioctl+0x947/0x1a40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3419
 do_vfs_ioctl+0x76a/0x1720 fs/ioctl.c:47
 ksys_ioctl fs/ioctl.c:742 [inline]
 __do_sys_ioctl fs/ioctl.c:749 [inline]
 __se_sys_ioctl fs/ioctl.c:747 [inline]
 __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747
 do_syscall_64+0xcb/0x150 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8881eaea1e80
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes inside of
 64-byte region [ffff8881eaea1e80, ffff8881eaea1ec0)
The buggy address belongs to the page:
page:ffffea0007aba840 refcount:1 mapcount:0 mapping:ffff8881f5c03180 index:0x0
flags: 0x8000000000000200(slab)
raw: 8000000000000200 ffffea0007a60680 0000000b0000000b ffff8881f5c03180
raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881eaea1d80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8881eaea1e00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8881eaea1e80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff8881eaea1f00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8881eaea1f80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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