linux-kernel - Re: [PATCH v6 5/5] usb: dwc3: implement gadget's quirk ep_out_align

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20131125210614.GP18046@saruman.home>
Date:	Mon, 25 Nov 2013 15:06:14 -0600
From:	Felipe Balbi <balbi@...com>
To:	David Cohen <david.a.cohen@...ux.intel.com>
CC:	<balbi@...com>, <gregkh@...uxfoundation.org>,
	<stern@...land.harvard.edu>, <mina86@...a86.com>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 5/5] usb: dwc3: implement gadget's quirk
 ep_out_align_size

Hi,

On Tue, Nov 12, 2013 at 01:04:46PM -0800, David Cohen wrote:
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 5452c0fce360..7c2d36f6ad4b 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1130,6 +1130,14 @@ static int dwc3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request,
>  	dev_vdbg(dwc->dev, "queing request %p to %s length %d\n",
>  			request, ep->name, request->length);
>  
> +	/* If ep out, roundup request->length to epout maxpacketsize */
> +	if (!(dep->number & 1)) {

we have a direction field in the dep structure, please use that.

> +		unsigned int aligned = roundup(request->length,
> +					       ep->desc->wMaxPacketSize);
> +		req->pad = aligned - request->length;
> +		request->length = aligned;

this is quite dangerous. You really don't know the size that gadget
driver allocated. What if we're using SLOB and gadget driver allocated
exactly 31 bytes (think MSC's CBW) ? Then you change request->length to
512-bytes (or 1024 if USB SS), and host happens to be buggy (or
exploited somehow) and sends more than 31-bytes ? You told dwc3 you
could receive more than 31-bytes even though you don't know what follows
your 31-byte buffer.

This is why I have been saying that gadget driver *must* be the one
hadnling this issue based on the quirk flag.

-- 
balbi

Download attachment "signature.asc" of type "application/pgp-signature" (837 bytes)