Re: [Qemu-devel] [PATCH 0/2] vmdk: Fix possible segfault with non-VMDK backing

[Max Reitz <mreitz@redhat.com>]

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On 2018-07-02 23:07, Max Reitz wrote:
> The VMDK driver assumes that its backing file is always a VMDK file,
> too, because it verifies that when creating the overlay.  However, that
> verification means nothing at runtime, and consequently you can assign
> non-VMDK backing files to a VMDK node.  This then breaks because the
> driver accesses the backing node as a VMDK node to read its supposed CID
> to compare it with the overlay's parentCID entry -- which usually fails,
> either in a benign way (we read from a garbage offset, and then we read
> garbage or get a read error straight away), or we get a segfault
> (because the backing node does not have a respective file child).
> 
> Anyway, we just shouldn't do it and instead check whether the backing
> file is a VMDK node before treating it like one.
> 
> 
> (This fixes
>  http://lists.nongnu.org/archive/html/qemu-block/2018-06/msg01268.html)
> 
> 
> Max Reitz (2):
>   vmdk: Fix possible segfault with non-VMDK backing
>   iotests: Add VMDK backing file correlation test
> 
>  block/vmdk.c               |   6 ++
>  tests/qemu-iotests/225     | 132 +++++++++++++++++++++++++++++++++++++
>  tests/qemu-iotests/225.out |  24 +++++++
>  tests/qemu-iotests/group   |   1 +
>  4 files changed, 163 insertions(+)
>  create mode 100755 tests/qemu-iotests/225
>  create mode 100644 tests/qemu-iotests/225.out

Applied to my block branch.

Max


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