[Qemu-devel] [Bug 1355697] [NEW] qemu-img: Segfault on a fuzzed image with large values of L1/L2 entries

[Qemu-devel] [Bug 1355697] [NEW] qemu-img: Segfault on a fuzzed image with large values of L1/L2 entries

[Maria Kustova]

Public bug reported:

'qemu-img check -r all/leaks' failed with a segmentation fault on the
fuzzed image with L1/L2 entry values having UINT64 border values.

Sequence:
 1. Unpack the attached archive, make a copy of test.img
 2. Put copy.img and backing_img.raw in the same directory
 3. Execute
   
qemu-img check -f qcow2 -r all copy.img

Result: qemu-img was killed by SIGSEGV.

The qemu-img execution log can be found in the attached archive.


qemu.git HEAD 2d591ce2aeebf

** Affects: qemu
     Importance: Undecided
         Status: New

** Attachment added: "images.n.traces.tar.gz"
   https://bugs.launchpad.net/bugs/1355697/+attachment/4175257/+files/images.n.traces.tar.gz

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https://bugs.launchpad.net/bugs/1355697

Title:
  qemu-img: Segfault on a fuzzed image with large values of L1/L2
  entries

Status in QEMU:
  New

Bug description:
  'qemu-img check -r all/leaks' failed with a segmentation fault on the
  fuzzed image with L1/L2 entry values having UINT64 border values.

  Sequence:
   1. Unpack the attached archive, make a copy of test.img
   2. Put copy.img and backing_img.raw in the same directory
   3. Execute
     
  qemu-img check -f qcow2 -r all copy.img

  Result: qemu-img was killed by SIGSEGV.

  The qemu-img execution log can be found in the attached archive.

  
  qemu.git HEAD 2d591ce2aeebf

To manage notifications about this bug go to:
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[Qemu-devel] [Bug 1355697] Re: qemu-img: Segfault on a fuzzed image with large values of L1/L2 entries

[Max Reitz]

Hi,

This issue has at least been partially fixed in master
(5f77ef69a195098baddfdc6d189f1b4a94587378):

$ ./qemu-img check -f qcow2 -r all copy.img
Warning: cluster offset=0xfffffffffe0000 is after the end of the image file, can't properly check refcounts.
Warning: cluster offset=0x100000000000000 is after the end of the image file, can't properly check refcounts.
ERROR l2_offset=fffffffffffe00: Table is not cluster aligned; L1 entry corrupted
Repairing cluster 0 refcount=0 reference=1
Repairing cluster 1 refcount=0 reference=1
qcow2: Marking image as corrupt: Preventing invalid write on metadata (overlaps with refcount table); further corruption events will be suppressed
Repairing cluster 21 refcount=0 reference=1

4 errors were found on the image.
Data may be corrupted, or further writes to the image may corrupt it.

2 internal errors have occurred during the check.
Image end offset: 2883584

I'm still working towards the repair function actually doing its job.

Thank you for your report,

Max

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https://bugs.launchpad.net/bugs/1355697

Title:
  qemu-img: Segfault on a fuzzed image with large values of L1/L2
  entries

Status in QEMU:
  Fix Committed

Bug description:
  'qemu-img check -r all/leaks' failed with a segmentation fault on the
  fuzzed image with L1/L2 entry values having UINT64 border values.

  Sequence:
   1. Unpack the attached archive, make a copy of test.img
   2. Put copy.img and backing_img.raw in the same directory
   3. Execute
     
  qemu-img check -f qcow2 -r all copy.img

  Result: qemu-img was killed by SIGSEGV.

  The qemu-img execution log can be found in the attached archive.

  
  qemu.git HEAD 2d591ce2aeebf

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1355697/+subscriptions

[Qemu-devel] [Bug 1355697] Re: qemu-img: Segfault on a fuzzed image with large values of L1/L2 entries

[Max Reitz]

Hi,

Okay, so this image has the same “issue” (it's intentionally broken, so
it's not really an issue) as the one in bug 1355738: There are corrupted
L2 entries which are impossible for qemu to repair. Therefore, we could
only ask the user to use qemu-img convert and that's all we can do.
Therefore, I'm marking this fixed as well.

Max

** Changed in: qemu
       Status: New => Fix Committed

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1355697

Title:
  qemu-img: Segfault on a fuzzed image with large values of L1/L2
  entries

Status in QEMU:
  Fix Committed

Bug description:
  'qemu-img check -r all/leaks' failed with a segmentation fault on the
  fuzzed image with L1/L2 entry values having UINT64 border values.

  Sequence:
   1. Unpack the attached archive, make a copy of test.img
   2. Put copy.img and backing_img.raw in the same directory
   3. Execute
     
  qemu-img check -f qcow2 -r all copy.img

  Result: qemu-img was killed by SIGSEGV.

  The qemu-img execution log can be found in the attached archive.

  
  qemu.git HEAD 2d591ce2aeebf

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1355697/+subscriptions

[Qemu-devel] [Bug 1355697] Re: qemu-img: Segfault on a fuzzed image with large values of L1/L2 entries

[T. Huth]

** Changed in: qemu
       Status: Fix Committed => Fix Released

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1355697

Title:
  qemu-img: Segfault on a fuzzed image with large values of L1/L2
  entries

Status in QEMU:
  Fix Released

Bug description:
  'qemu-img check -r all/leaks' failed with a segmentation fault on the
  fuzzed image with L1/L2 entry values having UINT64 border values.

  Sequence:
   1. Unpack the attached archive, make a copy of test.img
   2. Put copy.img and backing_img.raw in the same directory
   3. Execute
     
  qemu-img check -f qcow2 -r all copy.img

  Result: qemu-img was killed by SIGSEGV.

  The qemu-img execution log can be found in the attached archive.

  
  qemu.git HEAD 2d591ce2aeebf

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1355697/+subscriptions