Bug 729572

Summary: qcow2: Loading internal snapshot can corrupt image
Product: Red Hat Enterprise Linux 6 Reporter: Kevin Wolf <kwolf>
Component: qemu-kvmAssignee: Kevin Wolf <kwolf>
Status: CLOSED ERRATA QA Contact: Virtualization Bugs <virt-bugs>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 6.1CC: juzhang, mkenneth, qzhang, shuang, tburke, virt-maint
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: qemu-kvm-0.12.1.2-2.182.el6 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-12-06 15:55:57 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Kevin Wolf 2011-08-10 08:41:02 UTC 
We don't support internal snapshots, but it's not compiled out, this is an image corruption bug and upstream has a fix. So let's fix it anyway.

Reproducible with this script:

qemu-img create -f qcow2 /tmp/sn.qcow2 64M
qemu-img snapshot -c foo /tmp/sn.qcow2
qemu-io -c 'write -b 0 4M' /tmp/sn.qcow2
qemu-img snapshot -a foo /tmp/sn.qcow2
qemu-img check /tmp/sn.qcow2
Comment 5 juzhang 2011-08-31 07:15:11 UTC 
Reproduced this issue with qemu-kvm-0.12.1.2-2.180.el6 using comment0 steps.

Results:
#qemu-img check /tmp/sn.qcow2
ERROR cluster 1 refcount=0 reference=1
ERROR cluster 7 refcount=0 reference=1
ERROR cluster 8 refcount=0 reference=1
ERROR cluster 9 refcount=0 reference=1
ERROR cluster 10 refcount=0 reference=1
ERROR cluster 11 refcount=0 reference=1
ERROR cluster 12 refcount=0 reference=1
ERROR cluster 13 refcount=0 reference=1
ERROR cluster 14 refcount=0 reference=1
ERROR cluster 15 refcount=0 reference=1
ERROR cluster 16 refcount=0 reference=1

Verified this issue with  qemu-kvm-0.12.1.2-2.184.el6

Results:
#qemu-img check /tmp/sn.qcow2
No errors were found on the image.

This issue has been fixed.
Comment 7 errata-xmlrpc 2011-12-06 15:55:57 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-2011-1531.html