Re: [PATCH 1/2] qcow2: Limit total allocation range to INT_MAX

[Eric Blake <eblake@redhat.com>]

On 10/10/19 5:08 AM, Max Reitz wrote:
> When the COW areas are included, the size of an allocation can exceed
> INT_MAX.  This is kind of limited by handle_alloc() in that it already
> caps avail_bytes at INT_MAX, but the number of clusters still reflects
> the original length.
> 
> This can have all sorts of effects, ranging from the storage layer write
> call failing to image corruption.  (If there were no image corruption,
> then I suppose there would be data loss because the .cow_end area is
> forced to be empty, even though there might be something we need to
> COW.)
> 
> Fix all of it by limiting nb_clusters so the equivalent number of bytes
> will not exceed INT_MAX.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   block/qcow2-cluster.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)

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

-- 
Eric Blake, Principal Software Engineer
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