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 0332DC433EF for ; Tue, 26 Oct 2021 14:32:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D267560E08 for ; Tue, 26 Oct 2021 14:32:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235053AbhJZOfB (ORCPT ); Tue, 26 Oct 2021 10:35:01 -0400 Received: from smtp122.ord1c.emailsrvr.com ([108.166.43.122]:37215 "EHLO smtp122.ord1c.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234196AbhJZOey (ORCPT ); Tue, 26 Oct 2021 10:34:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mev.co.uk; s=20190130-41we5z8j; t=1635258750; bh=kyHbTTBR89/y1zbVw4a8imERHnNxgrB7fX9rUfytHHs=; h=Subject:To:From:Date:From; b=HioLFGLnR10LHJ7VdGfLvfFKk5YG1eOhpvWE6TKCjgUK/6qzBthXJcMm11HwnFike NmopkcjSPIqs9XOFNRYlU1lBwcQEBBC1yx3xxrrqvEGzOaPYni1yipqQ88Qtb7QHuE MtyMIxALsSqSUcSRh3hWljty5Jo4W6c6v9aGpME4= X-Auth-ID: abbotti@mev.co.uk Received: by smtp24.relay.ord1c.emailsrvr.com (Authenticated sender: abbotti-AT-mev.co.uk) with ESMTPSA id 3562A60196; Tue, 26 Oct 2021 10:32:29 -0400 (EDT) Subject: Re: [PATCH 3/5] comedi: vmk80xx: fix transfer-buffer overflows To: Johan Hovold , H Hartley Sweeten Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20211025114532.4599-1-johan@kernel.org> <20211025114532.4599-4-johan@kernel.org> From: Ian Abbott Organization: MEV Ltd. Message-ID: Date: Tue, 26 Oct 2021 15:32:28 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211025114532.4599-4-johan@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Classification-ID: ae72fbfa-5e41-4d86-8fff-d3f3be659ee3-1-1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/10/2021 12:45, Johan Hovold wrote: > The driver uses endpoint-sized USB transfer buffers but up until > recently had no sanity checks on the sizes. > > Commit e1f13c879a7c ("staging: comedi: check validity of wMaxPacketSize > of usb endpoints found") inadvertently fixed NULL-pointer dereferences > when accessing the transfer buffers in case a malicious device has a > zero wMaxPacketSize. > > Make sure to allocate buffers large enough to handle also the other > accesses that are done without a size check (e.g. byte 18 in > vmk80xx_cnt_insn_read() for the VMK8061_MODEL) to avoid writing beyond > the buffers, for example, when doing descriptor fuzzing. > > The original driver was for a low-speed device with 8-byte buffers. > Support was later added for a device that uses bulk transfers and is > presumably a full-speed device with a maximum 64-byte wMaxPacketSize. > > Fixes: 985cafccbf9b ("Staging: Comedi: vmk80xx: Add k8061 support") > Cc: stable@vger.kernel.org # 2.6.31 > Signed-off-by: Johan Hovold > --- > drivers/comedi/drivers/vmk80xx.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/comedi/drivers/vmk80xx.c b/drivers/comedi/drivers/vmk80xx.c > index 9f920819cd74..f2c1572d0cd7 100644 > --- a/drivers/comedi/drivers/vmk80xx.c > +++ b/drivers/comedi/drivers/vmk80xx.c > @@ -90,6 +90,8 @@ enum { > #define IC3_VERSION BIT(0) > #define IC6_VERSION BIT(1) > > +#define MIN_BUF_SIZE 64 > + > enum vmk80xx_model { > VMK8055_MODEL, > VMK8061_MODEL > @@ -678,12 +680,12 @@ static int vmk80xx_alloc_usb_buffers(struct comedi_device *dev) > struct vmk80xx_private *devpriv = dev->private; > size_t size; > > - size = usb_endpoint_maxp(devpriv->ep_rx); > + size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE); > devpriv->usb_rx_buf = kzalloc(size, GFP_KERNEL); > if (!devpriv->usb_rx_buf) > return -ENOMEM; > > - size = usb_endpoint_maxp(devpriv->ep_tx); > + size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE); > devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL); > if (!devpriv->usb_tx_buf) > return -ENOMEM; > Looks good, thanks! Reviewed-by: Ian Abbott -- -=( Ian Abbott || MEV Ltd. is a company )=- -=( registered in England & Wales. Regd. number: 02862268. )=- -=( Regd. addr.: S11 & 12 Building 67, Europa Business Park, )=- -=( Bird Hall Lane, STOCKPORT, SK3 0XA, UK. || www.mev.co.uk )=-