[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH for-2.11 5/5] qcow2: Refuse to get unaligned off

From: Eric Blake
Subject: Re: [Qemu-devel] [PATCH for-2.11 5/5] qcow2: Refuse to get unaligned offsets from cache
Date: Fri, 10 Nov 2017 16:15:34 -0600
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0

On 11/10/2017 04:00 PM, Max Reitz wrote:
>> Trying to understand this: we have a double corruption, because we
>> encountered a refblock that points outside of the image, but fixing the
>> refblock in turn encounters a second refblock that points within the
>> image but to an unaligned area.
> No, it's the very same.  As far as I've seen it, the repair function
> tries to fix the "refblock is outside image" error by resizing the image
> so the refblock is inside the image.  However, the subsequent
> bdrv_truncate() detects the alignment corruption, too, and thus marks
> the image corrupt.

Is resizing the image to be larger always a wise thing compared to just
rebuilding the refcount?  If I stick a large enough out-of-image value
in the table, can I cause a denial-of-service by making qemu try to
allocate petabytes of storage just to bring it into range?

Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Attachment: signature.asc
Description: OpenPGP digital signature

reply via email to

[Prev in Thread] Current Thread [Next in Thread]