Re: [Qemu-devel] [PATCH] mirror: Fail gracefully for source == target

[Eric Blake <eblake@redhat.com>]

On 08/14/2018 04:58 AM, Kevin Wolf wrote:
> blockdev-mirror with the same node for source and target segfaults
> today: A node is in its own backing chain, so mirror_start_job() decides
> that this is an active commit. When adding the intermediate nodes with
> block_job_add_bdrv(), it starts the iteration through the subchain with
> the backing file of source, though, so it never reaches target and
> instead runs into NULL at the base.
> 
> While we could fix that by starting with source itself, there is no
> point in allowing mirroring a node into itself and I wouldn't be
> surprised if this caused more problems later.
> 
> So just check for this scenario and error out.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   block/mirror.c             | 5 +++++
>   tests/qemu-iotests/041     | 6 ++++++
>   tests/qemu-iotests/041.out | 4 ++--
>   3 files changed, 13 insertions(+), 2 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
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