Re: [RFC v2 13/15] vfio/iommufd: Implement the iommufd backend

[Alistair Popple <apopple@nvidia.com>]

Yi Liu <yi.l.liu@intel.com> writes:

[...]

> +static int vfio_get_devicefd(const char *sysfs_path, Error **errp)
> +{
> +    long int ret = -ENOTTY;
> +    char *path, *vfio_dev_path = NULL, *vfio_path = NULL;
> +    DIR *dir;
> +    struct dirent *dent;
> +    gchar *contents;
> +    struct stat st;
> +    gsize length;
> +    int major, minor;
> +    dev_t vfio_devt;
> +
> +    path = g_strdup_printf("%s/vfio-device", sysfs_path);
> +    if (stat(path, &st) < 0) {
> +        error_setg_errno(errp, errno, "no such host device");
> +        goto out_free_path;
> +    }
> +
> +    dir = opendir(path);
> +    if (!dir) {
> +        error_setg_errno(errp, errno, "couldn't open dirrectory %s", path);
> +        goto out_free_path;
> +    }
> +
> +    while ((dent = readdir(dir))) {
> +        if (!strncmp(dent->d_name, "vfio", 4)) {
> +            vfio_dev_path = g_strdup_printf("%s/%s/dev", path, dent->d_name);
> +            break;
> +        }
> +    }
> +
> +    if (!vfio_dev_path) {
> +        error_setg(errp, "failed to find vfio-device/vfioX/dev");
> +        goto out_free_path;
> +    }
> +
> +    if (!g_file_get_contents(vfio_dev_path, &contents, &length, NULL)) {
> +        error_setg(errp, "failed to load \"%s\"", vfio_dev_path);
> +        goto out_free_dev_path;
> +    }
> +
> +    if (sscanf(contents, "%d:%d", &major, &minor) != 2) {
> +        error_setg(errp, "failed to get major:mino for \"%s\"", vfio_dev_path);
> +        goto out_free_dev_path;
> +    }
> +    g_free(contents);
> +    vfio_devt = makedev(major, minor);
> +
> +    vfio_path = g_strdup_printf("/dev/vfio/devices/%s", dent->d_name);
> +    ret = open_cdev(vfio_path, vfio_devt);
> +    if (ret < 0) {
> +        error_setg(errp, "Failed to open %s", vfio_path);
> +    }
> +
> +    trace_vfio_iommufd_get_devicefd(vfio_path, ret);
> +    g_free(vfio_path);
> +
> +out_free_dev_path:
> +    g_free(vfio_dev_path);
> +out_free_path:
> +    g_free(path);
> +
> +    if (*errp) {
> +        error_prepend(errp, VFIO_MSG_PREFIX, path);

I ran into this while trying to get things running, so haven't reviewed
the patch but noticed path is used after it's freed if !!*errp.

 - Alistair

> +    }
> +    return ret;
> +}