On 01/26/2017 04:18 AM, Daniel P. Berrange wrote: > The qcow driver refuses to open images which are less than > 2 bytes in size, but will happily create such images. Add > a check in the create path to avoid this discrepancy.
I agree that we have the 2-byte limit:
static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
...
if (header.size <= 1) {
error_setg(errp, "Image size is too small (must be at least 2
bytes)");
ret = -EINVAL;
goto fail;
}
But why 2 bytes? That's a weird limit from history. Oh well, no one
should be creating many new qcow images when we have qcow2, so I see no
problem with your patch as-is.
>
> Reviewed-by: Max Reitz <mre...@redhat.com>
> Signed-off-by: Daniel P. Berrange <berra...@redhat.com>
> ---
> block/qcow.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> +++ b/block/qcow.c
> @@ -799,6 +799,12 @@ static int qcow_create(const char *filename, QemuOpts
> *opts, Error **errp)
> /* Read out options */
> total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
> BDRV_SECTOR_SIZE);
> + if (total_size <= 1) {
It will never be 1 because of the ROUND_UP (it will either be 0 or a
sector size), but your code is defensive to match the open check.
Reviewed-by: Eric Blake <ebl...@redhat.com>
> + error_setg(errp, "Image size is too small, cannot be zero length");
> + ret = -EINVAL;
> + goto cleanup;
> + }
> +
> backing_file = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
> if (qemu_opt_get_bool_del(opts, BLOCK_OPT_ENCRYPT, false)) {
> flags |= BLOCK_FLAG_ENCRYPT;
>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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