Re: [Qemu-devel] [PATCH v1 2/3] qcow2: fix offset overflow

[Max Reitz <mreitz@redhat.com>]

On 30.12.2013 06:29, Hu Tao wrote:
> When cluster size is big enough it can lead offset overflow
> in qcow2_alloc_clusters_at(). This patch fixes it.
>
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> ---
>   block/qcow2-refcount.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index c974abe..b3ebb7f 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c
> @@ -676,7 +676,12 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
>       BDRVQcowState *s = bs->opaque;
>       uint64_t cluster_index;
>       uint64_t old_free_cluster_index;
> -    int i, refcount, ret;
> +    uint64_t i;
> +    int refcount, ret;
> +
> +    if (nb_clusters <= 0) {
> +        return 0;

I think I'd rather return -EINVAL here.

> +    }
>   
>       /* Check how many clusters there are free */
>       cluster_index = offset >> s->cluster_bits;