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    Subject[PATCH 5.4 001/149] KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio
    Date
    From: Kefeng Wang <wangkefeng.wang@huawei.com>

    commit 23fa2e46a5556f787ce2ea1a315d3ab93cced204 upstream.

    BUG: KASAN: use-after-free in kvm_vm_ioctl_unregister_coalesced_mmio+0x7c/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:183
    Read of size 8 at addr ffff0000c03a2500 by task syz-executor083/4269

    CPU: 5 PID: 4269 Comm: syz-executor083 Not tainted 5.10.0 #7
    Hardware name: linux,dummy-virt (DT)
    Call trace:
    dump_backtrace+0x0/0x2d0 arch/arm64/kernel/stacktrace.c:132
    show_stack+0x28/0x34 arch/arm64/kernel/stacktrace.c:196
    __dump_stack lib/dump_stack.c:77 [inline]
    dump_stack+0x110/0x164 lib/dump_stack.c:118
    print_address_description+0x78/0x5c8 mm/kasan/report.c:385
    __kasan_report mm/kasan/report.c:545 [inline]
    kasan_report+0x148/0x1e4 mm/kasan/report.c:562
    check_memory_region_inline mm/kasan/generic.c:183 [inline]
    __asan_load8+0xb4/0xbc mm/kasan/generic.c:252
    kvm_vm_ioctl_unregister_coalesced_mmio+0x7c/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:183
    kvm_vm_ioctl+0xe30/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3755
    vfs_ioctl fs/ioctl.c:48 [inline]
    __do_sys_ioctl fs/ioctl.c:753 [inline]
    __se_sys_ioctl fs/ioctl.c:739 [inline]
    __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739
    __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
    invoke_syscall arch/arm64/kernel/syscall.c:48 [inline]
    el0_svc_common arch/arm64/kernel/syscall.c:158 [inline]
    do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220
    el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367
    el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383
    el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670

    Allocated by task 4269:
    stack_trace_save+0x80/0xb8 kernel/stacktrace.c:121
    kasan_save_stack mm/kasan/common.c:48 [inline]
    kasan_set_track mm/kasan/common.c:56 [inline]
    __kasan_kmalloc+0xdc/0x120 mm/kasan/common.c:461
    kasan_kmalloc+0xc/0x14 mm/kasan/common.c:475
    kmem_cache_alloc_trace include/linux/slab.h:450 [inline]
    kmalloc include/linux/slab.h:552 [inline]
    kzalloc include/linux/slab.h:664 [inline]
    kvm_vm_ioctl_register_coalesced_mmio+0x78/0x1cc arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:146
    kvm_vm_ioctl+0x7e8/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3746
    vfs_ioctl fs/ioctl.c:48 [inline]
    __do_sys_ioctl fs/ioctl.c:753 [inline]
    __se_sys_ioctl fs/ioctl.c:739 [inline]
    __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739
    __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
    invoke_syscall arch/arm64/kernel/syscall.c:48 [inline]
    el0_svc_common arch/arm64/kernel/syscall.c:158 [inline]
    do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220
    el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367
    el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383
    el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670

    Freed by task 4269:
    stack_trace_save+0x80/0xb8 kernel/stacktrace.c:121
    kasan_save_stack mm/kasan/common.c:48 [inline]
    kasan_set_track+0x38/0x6c mm/kasan/common.c:56
    kasan_set_free_info+0x20/0x40 mm/kasan/generic.c:355
    __kasan_slab_free+0x124/0x150 mm/kasan/common.c:422
    kasan_slab_free+0x10/0x1c mm/kasan/common.c:431
    slab_free_hook mm/slub.c:1544 [inline]
    slab_free_freelist_hook mm/slub.c:1577 [inline]
    slab_free mm/slub.c:3142 [inline]
    kfree+0x104/0x38c mm/slub.c:4124
    coalesced_mmio_destructor+0x94/0xa4 arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:102
    kvm_iodevice_destructor include/kvm/iodev.h:61 [inline]
    kvm_io_bus_unregister_dev+0x248/0x280 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:4374
    kvm_vm_ioctl_unregister_coalesced_mmio+0x158/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:186
    kvm_vm_ioctl+0xe30/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3755
    vfs_ioctl fs/ioctl.c:48 [inline]
    __do_sys_ioctl fs/ioctl.c:753 [inline]
    __se_sys_ioctl fs/ioctl.c:739 [inline]
    __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739
    __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
    invoke_syscall arch/arm64/kernel/syscall.c:48 [inline]
    el0_svc_common arch/arm64/kernel/syscall.c:158 [inline]
    do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220
    el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367
    el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383
    el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670

    If kvm_io_bus_unregister_dev() return -ENOMEM, we already call kvm_iodevice_destructor()
    inside this function to delete 'struct kvm_coalesced_mmio_dev *dev' from list
    and free the dev, but kvm_iodevice_destructor() is called again, it will lead
    the above issue.

    Let's check the the return value of kvm_io_bus_unregister_dev(), only call
    kvm_iodevice_destructor() if the return value is 0.

    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: kvm@vger.kernel.org
    Reported-by: Hulk Robot <hulkci@huawei.com>
    Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
    Message-Id: <20210626070304.143456-1-wangkefeng.wang@huawei.com>
    Cc: stable@vger.kernel.org
    Fixes: 5d3c4c79384a ("KVM: Stop looking for coalesced MMIO zones if the bus is destroyed", 2021-04-20)
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    virt/kvm/coalesced_mmio.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/virt/kvm/coalesced_mmio.c
    +++ b/virt/kvm/coalesced_mmio.c
    @@ -190,7 +190,6 @@ int kvm_vm_ioctl_unregister_coalesced_mm
    coalesced_mmio_in_range(dev, zone->addr, zone->size)) {
    r = kvm_io_bus_unregister_dev(kvm,
    zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev);
    - kvm_iodevice_destructor(&dev->dev);

    /*
    * On failure, unregister destroys all devices on the
    @@ -200,6 +199,7 @@ int kvm_vm_ioctl_unregister_coalesced_mm
    */
    if (r)
    break;
    + kvm_iodevice_destructor(&dev->dev);
    }
    }


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