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Bug 889407 - snapshot --redefine disk snapshot may cause libvirtd crash
Summary: snapshot --redefine disk snapshot may cause libvirtd crash
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: libvirt
Version: 6.4
Hardware: x86_64
OS: Linux
high
high
Target Milestone: rc
: ---
Assignee: Peter Krempa
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks: 895654
TreeView+ depends on / blocked
 
Reported: 2012-12-21 05:05 UTC by weizhang
Modified: 2013-02-21 07:29 UTC (History)
9 users (show)

Fixed In Version: libvirt-0.10.2-15.el6
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2013-02-21 07:29:27 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
libvirtd crash log (64.06 KB, text/plain)
2012-12-21 05:05 UTC, weizhang 		no flags Details
View All


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2013:0276 0 normal SHIPPED_LIVE Moderate: libvirt security, bug fix, and enhancement update 2013-02-20 21:18:26 UTC

Description weizhang 2012-12-21 05:05:52 UTC 
Created attachment 667100 [details]
libvirtd crash log

Description of problem:
after create disk snapshot for shutdown guest and redefine it, It may cause libvirtd crash


Version-Release number of selected component (if applicable):
libvirt-0.10.2-13.el6.x86_64
qemu-kvm-0.12.1.2-2.346.el6.x86_64
kernel-2.6.32-348.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1. prepare a shutdown guest
2. create snapshot with
#  virsh snapshot-create tt sn-tck1.xml --reuse-external --quiesce --disk-only
# cat sn-tck1.xml
<domainsnapshot>
  <name>snapshot-tck1</name>
  <state>shutoff</state>
  <creationTime>1356059598</creationTime>
  <memory snapshot='no'/>
  <disks>
    <disk name='vda' snapshot='external'>
      <driver type='qcow2'/>
      <source file='/var/lib/libvirt/images/images/tt.snapshot-tck1'/>
    </disk>
  </disks>
</domainsnapshot>
3. redefine snapshot
#  virsh snapshot-create tt snapshot-tt.xml --redefine
  
Actual results:
libvirtd crash
error: End of file while reading data: Input/output error
error: Failed to reconnect to the hypervisor

Expected results:
libvirtd works well

Additional info:
Comment 1 Peter Krempa 2013-01-05 07:54:17 UTC 
Fixed upstream:

commit 709b0f37c5cb22b8846e59c2259ea30e73d72d92
Author: Peter Krempa <pkrempa>
Date:   Thu Jan 3 14:20:09 2013 +0100

    snapshot: qemu: Fix segfault and vanishing snapshots when redefining
    
    When the disk alignment check done while redefining an existing snapshot
    failed, the qemu driver attempted to free the existing snapshot. As in
    the cleanup path the definition of the snapshot wasn't assigned, the
    cleanup code dereferenced a NULL pointer.
    
    This patch changes the behavior on error paths while redefining snapshot
    in two ways:
    
    1) On failure, modifications done on the snapshot definition object are
    rolled back.
    
    2) The previous definition of the data isn't freed until it's certain it
    won't be needed any more.
    
    This change avoids the segfault and additionally the snapshot doesn't
    vanish if redefinition fails for some reason.
Comment 4 zhe peng 2013-01-10 06:34:14 UTC 
I can reproduce this with build : libvirt-0.10.2-14.el6.x86_64
verify on libvirt-0.10.2-15.el6.x86_64

step:
1:prepare a shutdown guest
2:create snapshot with:
#  virsh snapshot-create rhel6.3 rhel-sn.xml --reuse-external --quiesce --disk-only
# cat rhel-sn.xml
<domainsnapshot>
  <name>snapshot-rhel6.3</name>
    <state>shutoff</state>
    <creationTime>1356059598</creationTime>
    <memory snapshot='no'/>
       <disks>
        <disk name='hda' snapshot='external'>
        <driver type='qcow2'/>
        <source file='/var/lib/libvirt/images/rhel6.3.img'/>
        </disk>
       </disks>
</domainsnapshot>

3. redefine snapshot
# virsh snapshot-create rhel6.3 rhel-sn.xml --redefine
Domain snapshot snapshot-rhel6.3 created from 'rhel-sn.xml'

libvirtd not crash, verification passed.
Comment 5 errata-xmlrpc 2013-02-21 07:29:27 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2013-0276.html
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