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

[Max Reitz]

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

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2.17.1