Re: [Qemu-block] [PATCH 10/10] scsi: add persistent reservation manager using qemu-pr-helper

[Stefan Hajnoczi]

On Tue, Aug 22, 2017 at 03:18:32PM +0200, Paolo Bonzini wrote:
> +/* Called with lock held.  */
> +static int pr_manager_helper_read(PRManagerHelper *pr_mgr,
> +                                  void *buf, int sz, Error **errp)
> +{
> +    ssize_t r = qio_channel_read_all(pr_mgr->ioc, buf, sz, errp);
> +
> +    if (r < 0) {
> +        object_unref(OBJECT(pr_mgr->ioc));
> +        pr_mgr->ioc = NULL;
> +        return r;
> +    }
> +
> +    return r < 0 ? r : 0;

At this point we know r >= 0:

  return r;

> +    if (pr_manager_helper_read(pr_mgr, &resp, sizeof(resp), NULL) < 0) {
> +        ret = -EINVAL;
> +        goto out;
> +    }

resp.result is big-endian and accessed without byteswaps below.  We
need:

  resp.result = be32_to_host(resp.result);

> +    if (expected_dir == SG_DXFER_FROM_DEV && resp.result == 0) {
> +        if (pr_manager_helper_read(pr_mgr, io_hdr->dxferp, len, NULL) < 0) {
> +            ret = -EINVAL;
> +            goto out;
> +        }
> +    }
> +
> +    io_hdr->status = resp.result;
> +    if (resp.result == CHECK_CONDITION) {
> +        io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
> +        io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, PR_HELPER_SENSE_SIZE);
> +        memcpy(io_hdr->sbp, resp.sense, io_hdr->sb_len_wr);
> +    }
> +
> +out:
> +    if (ret < 0) {
> +        int sense_len = scsi_build_sense(io_hdr->sbp,
> +                                         SENSE_CODE(LUN_COMM_FAILURE));
> +        io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
> +        io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, sense_len);
> +        io_hdr->status = CHECK_CONDITION;
> +    }
> +    qemu_mutex_unlock(&pr_mgr->lock);
> +    return ret;
> +}
> +static void pr_manager_helper_instance_finalize(Object *obj)
> +{
> +    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
> +
> +    g_free(pr_mgr->path);

Double free, the "path" property already has a release function that
frees the string.