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From: Max Reitz <mreitz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 3/4] qcow2: Don't open images with
 header.refcount_table_clusters == 0
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To: Alberto Garcia <berto@igalia.com>, qemu-devel@nongnu.org
Cc: qemu-block@nongnu.org, Kevin Wolf <kwolf@redhat.com>, Thomas Huth <thuth@redhat.com>, "R . Nageswara Sastry" <nasastry@in.ibm.com>

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From: Max Reitz <mreitz@redhat.com>
To: Alberto Garcia <berto@igalia.com>, qemu-devel@nongnu.org
Cc: qemu-block@nongnu.org, Kevin Wolf <kwolf@redhat.com>,
 Thomas Huth <thuth@redhat.com>, "R . Nageswara Sastry" <nasastry@in.ibm.com>
Message-ID: <6e9b5351-b1b4-4df4-c267-a8b4e8061864@redhat.com>
Subject: Re: [PATCH 3/4] qcow2: Don't open images with
 header.refcount_table_clusters == 0
References: <cover.1509550787.git.berto@igalia.com>
 <33492fad2f21dff38a33a96decb38983aee7e405.1509550787.git.berto@igalia.com>
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On 2017-11-01 16:42, Alberto Garcia wrote:
> qcow2_do_open() is checking that header.refcount_table_clusters is not
> too large, but it doesn't check that it's greater than zero. Apart
> from the fact that an image like that is obviously corrupted, trying
> to use it crashes QEMU since we end up with a null s->refcount_table
> after qcow2_refcount_init().
>=20
> These images can however be repaired, so allow opening them if the
> BDRV_O_CHECK flag is set.
>=20
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>  block/qcow2.c              | 6 ++++++
>  tests/qemu-iotests/060     | 7 +++++++
>  tests/qemu-iotests/060.out | 5 +++++
>  3 files changed, 18 insertions(+)

Reviewed-by: Max Reitz <mreitz@redhat.com>


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