Re: [PATCH] usb/storage: clear csw on reset - Philippe Mathieu-Daudé

From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
To: Gerd Hoffmann <kraxel@redhat.com>, qemu-devel@nongnu.org
Subject: Re: [PATCH] usb/storage: clear csw on reset
Date: Fri, 12 Mar 2021 11:01:10 +0100	[thread overview]
Message-ID: <120ee673-b1e8-44ea-eb7a-e98d017a3aec@redhat.com> (raw)
In-Reply-To: <20210312094954.796799-1-kraxel@redhat.com>

On 3/12/21 10:49 AM, Gerd Hoffmann wrote:
> Stale data in csw (specifically residue) can confuse the state machine
> and allows the guest trigger an assert().  So clear csw on reset to
> avoid this happening in case the guest resets the device in the middle
> of a request.
> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1523811
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/usb/dev-storage.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
> index a5f76fc00120..fd4ea818115c 100644
> --- a/hw/usb/dev-storage.c
> +++ b/hw/usb/dev-storage.c
> @@ -352,6 +352,7 @@ static void usb_msd_handle_reset(USBDevice *dev)
>          usb_msd_packet_complete(s);
>      }
>  
> +    memset(&s->csw, 0, sizeof(s->csw));

easy-peasy...

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

>      s->mode = USB_MSDM_CBW;
>  }