Re: [Qemu-devel] [PULL 5/5] usb-mtp: Advertise SendObjectInfo for write support

[Peter Maydell]

On 27 February 2018 at 08:39, Gerd Hoffmann <address@hidden> wrote:
> From: Bandan Das <address@hidden>
>
> This patch implements a dummy ObjectInfo structure so that
> it's easy to typecast the incoming data. If the metadata is
> valid, write_pending is set. Also, the incoming filename
> is utf-16, so, instead of depending on external libraries, just
> implement a simple function to get the filename

> +static void usb_mtp_write_metadata(MTPState *s)

Hi; Coverity points out a missing error check in this function
(CID 1390578):

> +{
> +    MTPData *d = s->data_out;
> +    ObjectInfo *dataset = (ObjectInfo *)d->data;
> +    char *filename = g_new0(char, dataset->length);
> +    MTPObject *o;
> +    MTPObject *p = usb_mtp_object_lookup(s, s->dataset.parent_handle);

usb_mtp_object_lookup() can return NULL, but we do not check it...

> +    uint32_t next_handle = s->next_handle;
> +
> +    assert(!s->write_pending);
> +
> +    utf16_to_str(dataset->length, dataset->filename, filename);
> +
> +    o = usb_mtp_object_lookup_name(p, filename, dataset->length);

...and if p is NULL here then we will crash in usb_mtp_object_lookup_name().

> +    if (o != NULL) {
> +        next_handle = o->handle;
> +    }
> +
> +    s->dataset.filename = filename;
> +    s->dataset.format = dataset->format;
> +    s->dataset.size = dataset->size;
> +    s->dataset.filename = filename;
> +    s->write_pending = true;
> +
> +    if (s->dataset.format == FMT_ASSOCIATION) {
> +        usb_mtp_write_data(s);
> +        /* next_handle will be allocated to the newly created dir */
> +        if (d->fd == -1) {
> +            usb_mtp_queue_result(s, RES_STORE_FULL, d->trans,
> +                                 0, 0, 0, 0);
> +            return;
> +        }
> +        d->fd = -1;
> +    }
> +
> +    usb_mtp_queue_result(s, RES_OK, d->trans, 3, QEMU_STORAGE_ID,
> +                         s->dataset.parent_handle, next_handle);
> +}
> +

thanks
-- PMM