[Qemu-devel] [Bug 1462944] Re: vpc file causes qemu-img to consume lots of time and memory

[Richard Jones]

I suspect this bug is probably still around, and if not then this class
of bugs is certainly still around.  What we have done in management
tools like Open Stack is to confine qemu-img using simple ulimits when
inspecting any untrusted image, and that solves the problem so it's
probably fine to close this bug now.

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https://bugs.launchpad.net/bugs/1462944

Title:
  vpc file causes qemu-img to consume lots of time and memory

Status in QEMU:
  Incomplete

Bug description:
  The attached vpc file causes 'qemu-img info' to consume 3 or 4 seconds
  of CPU time and 1.3 GB of heap, causing a minor denial of service.

  $ /usr/bin/time ~/d/qemu/qemu-img info afl12.img
  block-vpc: The header checksum of 'afl12.img' is incorrect.
  qemu-img: Could not open 'afl12.img': block-vpc: free_data_block_offset 
points after the end of file. The image has been truncated.
  1.19user 3.15system 0:04.35elapsed 99%CPU (0avgtext+0avgdata 
1324504maxresident)k
  0inputs+0outputs (0major+327314minor)pagefaults 0swaps

  The file was found using american-fuzzy-lop.

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