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Re: [Qemu-devel] [PATCH v2] qcow2: fix preallocation with metadata on ba
From: |
Ivan Ren |
Subject: |
Re: [Qemu-devel] [PATCH v2] qcow2: fix preallocation with metadata on bare block device |
Date: |
Fri, 11 May 2018 22:40:48 +0800 |
>> Create a qcow2 directly on bare block device with
>> "-o preallocation=metadata" option. When read this qcow2, it will
>> return pre-existing data on block device, and this may lead to
>> data leakage. This patch add QCOW_OFLAG_ZERO for all preallocated
>> l2 entry to avoid this problem.
>
> This is a semantic change; are we okay making it?
> Does your code properly check for qcow2v2 files, which don't support
> QCOW_OFLAG_ZERO (only qcow2v3 supports it)?
Sorry for this mistake.
Current solution can only be used with s->qcow_version >= 3.
I'll fix it.
On Fri, May 11, 2018 at 9:41 PM Eric Blake <address@hidden> wrote:
> On 05/11/2018 07:37 AM, Ivan Ren wrote:
> > Create a qcow2 directly on bare block device with
> > "-o preallocation=metadata" option. When read this qcow2, it will
> > return pre-existing data on block device, and this may lead to
> > data leakage. This patch add QCOW_OFLAG_ZERO for all preallocated
> > l2 entry to avoid this problem.
>
> This is a semantic change; are we okay making it?
>
> Does your code properly check for qcow2v2 files, which don't support
> QCOW_OFLAG_ZERO (only qcow2v3 supports it)?
>
> >
> > Signed-off-by: Ivan Ren <address@hidden>
> > ---
>
> --
> Eric Blake, Principal Software Engineer
> Red Hat, Inc. +1-919-301-3266
> Virtualization: qemu.org | libvirt.org
>