Re: [Qemu-devel] [PULL 2/4] usb-mtp: fix some usb_mtp_write_data return paths

[Peter Maydell <peter.maydell@linaro.org>]

On Thu, 7 Mar 2019 at 09:58, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> From: Bandan Das <bsd@redhat.com>
>
> During a write, free up the "path" before getting more data.
> Also, while we at it, remove the confusing usage of d->fd for
> storing mkdir status
>
> Spotted by Coverity: CID 1398642
>
> Signed-off-by: Bandan Das <bsd@redhat.com>
> Message-id: 20190306210409.14842-3-bsd@redhat.com
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Hi; Coverity found an issue with the code change here
(CID 1399415):

> index 4dde14fc7887..1f22284949df 100644
> --- a/hw/usb/dev-mtp.c
> +++ b/hw/usb/dev-mtp.c
> @@ -1605,7 +1605,7 @@ static int usb_mtp_update_object(MTPObject *parent, char *name)
>      return ret;
>  }
>
> -static void usb_mtp_write_data(MTPState *s)
> +static int usb_mtp_write_data(MTPState *s)

Here we change usb_mtp_write_data() to return an error code...

>  {
>      MTPData *d = s->data_out;
>      MTPObject *parent =

> @@ -1727,14 +1731,12 @@ static void usb_mtp_write_metadata(MTPState *s, uint64_t dlen)
>      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) {
> +        if (usb_mtp_write_data(s)) {
> +            /* next_handle will be allocated to the newly created dir */
>              usb_mtp_queue_result(s, RES_STORE_FULL, d->trans,
>                                   0, 0, 0, 0);
>              return;

...and we updated this callsite to check the error return value.

But the two places in usb_mtp_get_data() that call
usb_mtp_write_metadata() still don't check its return
value: don't they need to handle failure too?

thanks
-- PMM