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 ffff88809d011080 by task syz-executor.3/8040 CPU: 1 PID: 8040 Comm: syz-executor.3 Not tainted 4.14.222-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: 0033:0x465ef9 RSP: 002b:00007f57bdc61188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465ef9 RDX: 0000000020000200 RSI: 000000004010ae68 RDI: 0000000000000004 RBP: 00007f57bdc611d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007fffb337339f R14: 00007f57bdc61300 R15: 0000000000022000 Allocated by task 8040: 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 8040: 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 ffff88809d011080 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes inside of 64-byte region [ffff88809d011080, ffff88809d0110c0) The buggy address belongs to the page: page:ffffea0002740440 count:1 mapcount:0 mapping:ffff88809d011000 index:0xffff88809d011e80 flags: 0xfff00000000100(slab) raw: 00fff00000000100 ffff88809d011000 ffff88809d011e80 000000010000000b raw: ffffea00026b99e0 ffffea00025ca460 ffff88813fe80340 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809d010f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88809d011000: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc >ffff88809d011080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff88809d011100: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88809d011180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================