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 1FB86C4332F for ; Tue, 26 Oct 2021 11:15:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 042EF60F24 for ; Tue, 26 Oct 2021 11:15:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235405AbhJZLSK (ORCPT ); Tue, 26 Oct 2021 07:18:10 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:45352 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230308AbhJZLSI (ORCPT ); Tue, 26 Oct 2021 07:18:08 -0400 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 196243F0; Tue, 26 Oct 2021 13:15:43 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1635246943; bh=WxA0PSLaqHfqEyChJwTJYKvReBL3f+/2oUC5lcN5GHE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ucXfWtQUi5q+VLNAVYwATavzowlEIhtqsygINS7W+DRWUsI8RE+sb1aFgq93u2VPB K73haXlDyxHFXzDYcf17TUahjEZJIeQHvIDlEkKudUF2cnNgqRlPOdRyw/QbhtybJ7 zcEFCevaqgsHsVyJhEZLuT/qO8QCC5/LeGb6ZADk= Date: Tue, 26 Oct 2021 14:15:20 +0300 From: Laurent Pinchart To: Kieran Bingham Cc: Johan Hovold , 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=utf-8 Content-Disposition: inline In-Reply-To: <163524570516.1184428.14632987312253060787@Monstersaurus> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 ? > But either way, this seems sane. > > Reviewed-by: Kieran Bingham > > > + > > ret = uvc_init_video_bulk(stream, ep, gfp_flags); > > } > > -- Regards, Laurent Pinchart