[Qemu-devel] [Bug 1354529] Re: qemu-io: Assert failure on the fuzzed qcow2 image

[Max Reitz]

Hi,

The problem here is that an L2 table contains an offset which is not
aligned on cluster boundaries. To turn the failed assertion into an EIO
(and probably we also want to mark the image corrupt), we'd have to
verify every single L2 entry when it is read.

We can (and should) most certainly do that, but as it doesn't seem too
urgent, it may take some time.

Max

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https://bugs.launchpad.net/bugs/1354529

Title:
  qemu-io: Assert failure on the fuzzed qcow2 image

Status in QEMU:
  New

Bug description:
  'qemu-io -c write' failed on the fuzzed image with missed refcount
  tables:

  Sequence:
   1. Unpack the attached archive, make a copy of test.img
   2. Put copy.img and backing_img.cow in the same directory
   3. Execute
     qemu-io copy.img -c 'write 2856960 208896'

  Result: qemu-io was killed by SIGIOT with the reason:

  qemu-io: block/qcow2-cluster.c:910: handle_copied: Assertion `*host_offset == 
0 
  || offset_into_cluster(s, guest_offset) == offset_into_cluster(s, 
*host_offset)'
   failed.

  qemu.git HEAD 2d591ce2aeebf

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