Re: [Qemu-devel] [PATCH v5] raw_bsd: add offset and size options

["Tomáš Golembiovský" <tgolembi@redhat.com>]

I should test my code more before submitting it to ML. I have found two
bugs in the patch.


On Sun, 23 Oct 2016 16:54:37 +0200
Tomáš Golembiovský <tgolembi@redhat.com> wrote:

> +static int raw_read_options(QDict *options, BlockDriverState *bs,
> +    BDRVRawState *s, Error **errp)
> +{
> +    Error *local_err = NULL;
> +    QemuOpts *opts = NULL;
> +    int64_t real_size = 0;
> +    int ret;
> +
> +    real_size = bdrv_getlength(bs->file->bs);
> +    if (real_size < 0) {
> +        error_setg_errno(errp, -real_size, "Could not get image size");
> +        return real_size;
> +    }
> +
> +    opts = qemu_opts_create(&raw_runtime_opts, NULL, 0, &error_abort);
> +    qemu_opts_absorb_qdict(opts, options, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        ret = -EINVAL;
> +        goto end;
> +    }
> +
> +    s->offset = qemu_opt_get_size(opts, "offset", 0);
> +    if (qemu_opt_find(opts, "size") != NULL) {
> +        s->size = qemu_opt_get_size(opts, "size", 0);
> +        s->has_size = true;
> +    } else {
> +        s->has_size = false;
> +        s->size = real_size;

This has to be:

        s->size = real_size - s->offset;

.. to account for the offset. Otherwise the following check will fail.

> +    }
> +
> +    /* Check size and offset */
> +    if (real_size < s->offset || (real_size - s->offset) < s->size) {
> +        error_setg(errp, "The sum of offset (%" PRIu64 ") and size "
> +            "(%" PRIu64 ") has to be smaller or equal to the "
> +            " actual size of the containing file (%" PRId64 ")",
> +            s->offset, s->size, real_size);
> +        ret = -EINVAL;
> +        goto end;
> +    }
> +
> +    /* Make sure size is multiple of BDRV_SECTOR_SIZE to prevent rounding
> +     * up and leaking out of the specified area. */
> +    if (QEMU_IS_ALIGNED(s->size, BDRV_SECTOR_SIZE)) {

The condition has to be negated. Silly mistake made while rewriting the
condition to use QEMU_IS_ALIGNED.

> +        error_setg(errp, "Specified size is not multiple of %llu",
> +            BDRV_SECTOR_SIZE);
> +        ret = -EINVAL;
> +        goto end;
> +    }
> +
> +    ret = 0;
> +
> +end:
> +
> +    qemu_opts_del(opts);
> +
> +    return ret;
> +}
> +

-- 
Tomáš Golembiovský <tgolembi@redhat.com>