From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8851EC433FE for ; Tue, 26 Oct 2021 12:07:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 689826054E for ; Tue, 26 Oct 2021 12:07:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234268AbhJZMJj (ORCPT ); Tue, 26 Oct 2021 08:09:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:37244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233838AbhJZMJg (ORCPT ); Tue, 26 Oct 2021 08:09:36 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6E88960E05; Tue, 26 Oct 2021 12:07:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1635250032; bh=5UPpA3J3tlAokOz6B34fDtDFsO0+mmeco3ZVTn3rKOg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=a6mfWS66LrSGEjYVEif3tz+5FEp0/Y3oKJopxn5uS7/SH0k5SnfJSm04RJOEOk8fk 6KG6qPkzoRcF6JCwd0M0mrp1YSs0QAuqBR6B0X/OpeyT07njShauhD7ocDmpw55O+5 IErBq4AFG+C64i9xRDN9ODPUbT+vUFUMsYewbLxAqcVfyYP5PgGZ70aLXonTCxzvHd KdLmjZ6I/DW2tnrtkxSWWz/jTUFybwj9xTQllfW9fgOq9t3/TKnsiO8AY8F47nc70W /fht8AbY0nwFBhP1mHY00++qb5bOw22i43yAshblzPShk4vKirskrb6nac9PB0poBS g4IBREQ0dIq+A== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1mfLEF-0001fI-Ns; Tue, 26 Oct 2021 14:06:56 +0200 Date: Tue, 26 Oct 2021 14:06:55 +0200 From: Johan Hovold To: Laurent Pinchart Cc: Kieran Bingham , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] media: uvcvideo: fix division by zero at stream start Message-ID: References: <20211026095511.26673-1-johan@kernel.org> <163524570516.1184428.14632987312253060787@Monstersaurus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 26, 2021 at 02:15:20PM +0300, Laurent Pinchart wrote: > On Tue, Oct 26, 2021 at 11:55:05AM +0100, Kieran Bingham wrote: > > Quoting Johan Hovold (2021-10-26 10:55:11) > > > Add the missing bulk-endpoint max-packet sanity check to probe() to > > > avoid division by zero in uvc_alloc_urb_buffers() in case a malicious > > > device has broken descriptors (or when doing descriptor fuzz testing). > > > > > > Note that USB core will reject URBs submitted for endpoints with zero > > > wMaxPacketSize but that drivers doing packet-size calculations still > > > need to handle this (cf. commit 2548288b4fb0 ("USB: Fix: Don't skip > > > endpoint descriptors with maxpacket=0")). > > > > > > Fixes: c0efd232929c ("V4L/DVB (8145a): USB Video Class driver") > > > Cc: stable@vger.kernel.org # 2.6.26 > > > Signed-off-by: Johan Hovold > > > --- > > > drivers/media/usb/uvc/uvc_video.c | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > > > index e16464606b14..85ac5c1081b6 100644 > > > --- a/drivers/media/usb/uvc/uvc_video.c > > > +++ b/drivers/media/usb/uvc/uvc_video.c > > > @@ -1958,6 +1958,10 @@ static int uvc_video_start_transfer(struct uvc_streaming *stream, > > > if (ep == NULL) > > > return -EIO; > > > > > > + /* Reject broken descriptors. */ > > > + if (usb_endpoint_maxp(&ep->desc) == 0) > > > + return -EIO; > > > > Is there any value in identifying this with a specific return code like > > -ENODATA? > > Going one step further, wouldn't it be better to fail probe() for those > devices ? This is not how the driver works today. Look at the "return -EIO" just above in case the expected endpoint is missing. And similarly for the isochronous case for which zero wMaxPacket isn't handled until uvc_video_start_transfer() either (a few lines further up still). Note however the copy-paste error in the commit message mentioning probe(), which is indeed where this would typically be handled. Do you want me to resend or can you change s/probe()/uvc_video_start_transfer()/ in the commit message when applying if you think this is acceptable as is? Johan