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 X-Spam-Level: X-Spam-Status: No, score=-12.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37377C43381 for ; Mon, 18 Mar 2019 07:00:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ECFBB2083D for ; Mon, 18 Mar 2019 07:00:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552892406; bh=BCXQgf58qScp81kMkgmwSLJ4BRJPbQytbkp4w0w85Xc=; h=Subject:To:From:Date:List-ID:From; b=PIGJnKOUaVnI5tloBUtAatw42Gw+g1xnUk5IRa8zcoSI8vKlpMRub+V8fa+Hr1lqE pVfZsiGKXdJBxhSEi3nAoh0e4/g+icNZIHUZQ1xcGHbLdTJreg1AZAxRUOocVR0V9o ZqgnPRTaR72a78o7KoeXFx5pkMrkG9vlzdrkrB4g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727768AbfCRHAF (ORCPT ); Mon, 18 Mar 2019 03:00:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:44556 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726135AbfCRHAF (ORCPT ); Mon, 18 Mar 2019 03:00:05 -0400 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AE85D2077B; Mon, 18 Mar 2019 07:00:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552892404; bh=BCXQgf58qScp81kMkgmwSLJ4BRJPbQytbkp4w0w85Xc=; h=Subject:To:From:Date:From; b=2peu7vSztSfkNAFajKeg8ljzprI8ZrW1Cf9Z73xtgLujnvtjAdpPMeafQrtmYvJCD IVj7SsMyJAw1aOW9Xmr2IpGXY8NrrvbNw9XJh3w2z32BYnyLVGIKHvKATR+kl0nBOO bwRjm+lQYG9ENAsgiw7oh27znDCKCaWPVOx6hrtc= Subject: patch "staging: comedi: ni_mio_common: Fix divide-by-zero for DIO cmdtest" added to staging-linus To: abbotti@mev.co.uk, grabesstimme@gmail.com, gregkh@linuxfoundation.org, olsonse@umich.edu, stable@vger.kernel.org From: Date: Mon, 18 Mar 2019 08:00:01 +0100 Message-ID: <155289240125030@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled staging: comedi: ni_mio_common: Fix divide-by-zero for DIO cmdtest to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From bafd9c64056cd034a1174dcadb65cd3b294ff8f6 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Mon, 4 Mar 2019 14:33:54 +0000 Subject: staging: comedi: ni_mio_common: Fix divide-by-zero for DIO cmdtest `ni_cdio_cmdtest()` validates Comedi asynchronous commands for the DIO subdevice (subdevice 2) of supported National Instruments M-series cards. It is called when handling the `COMEDI_CMD` and `COMEDI_CMDTEST` ioctls for this subdevice. There are two causes for a possible divide-by-zero error when validating that the `stop_arg` member of the passed-in command is not too large. The first cause for the divide-by-zero is that calls to `comedi_bytes_per_scan()` are only valid once the command has been copied to `s->async->cmd`, but that copy is only done for the `COMEDI_CMD` ioctl. For the `COMEDI_CMDTEST` ioctl, it will use whatever was left there by the previous `COMEDI_CMD` ioctl, if any. (This is very likely, as it is usual for the application to use `COMEDI_CMDTEST` before `COMEDI_CMD`.) If there has been no previous, valid `COMEDI_CMD` for this subdevice, then `comedi_bytes_per_scan()` will return 0, so the subsequent division in `ni_cdio_cmdtest()` of `s->async->prealloc_bufsz / comedi_bytes_per_scan(s)` will be a divide-by-zero error. To fix this error, call a new function `comedi_bytes_per_scan_cmd(s, cmd)`, based on the existing `comedi_bytes_per_scan(s)` but using a specified `struct comedi_cmd` for its calculations. (Also refactor `comedi_bytes_per_scan()` to call the new function.) Once the first cause for the divide-by-zero has been fixed, the second cause is that `comedi_bytes_per_scan_cmd()` can legitimately return 0 if the `scan_end_arg` member of the `struct comedi_cmd` being tested is 0. Fix it by only performing the division (and validating that `stop_arg` is no more than the maximum value) if `comedi_bytes_per_scan_cmd()` returns a non-zero value. The problem was reported on the COMEDI mailing list here: https://groups.google.com/forum/#!topic/comedi_list/4t9WlHzMhKM Reported-by: Ivan Vasilyev Tested-by: Ivan Vasilyev Fixes: f164cbf98fa8 ("staging: comedi: ni_mio_common: add finite regeneration to dio output") Cc: # 4.6+ Cc: Spencer E. Olson Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/comedidev.h | 2 ++ drivers/staging/comedi/drivers.c | 33 ++++++++++++++++--- .../staging/comedi/drivers/ni_mio_common.c | 10 ++++-- 3 files changed, 38 insertions(+), 7 deletions(-) diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h index a7d569cfca5d..0dff1ac057cd 100644 --- a/drivers/staging/comedi/comedidev.h +++ b/drivers/staging/comedi/comedidev.h @@ -1001,6 +1001,8 @@ int comedi_dio_insn_config(struct comedi_device *dev, unsigned int mask); unsigned int comedi_dio_update_state(struct comedi_subdevice *s, unsigned int *data); +unsigned int comedi_bytes_per_scan_cmd(struct comedi_subdevice *s, + struct comedi_cmd *cmd); unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s); unsigned int comedi_nscans_left(struct comedi_subdevice *s, unsigned int nscans); diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c index eefa62f42c0f..5a32b8fc000e 100644 --- a/drivers/staging/comedi/drivers.c +++ b/drivers/staging/comedi/drivers.c @@ -394,11 +394,13 @@ unsigned int comedi_dio_update_state(struct comedi_subdevice *s, EXPORT_SYMBOL_GPL(comedi_dio_update_state); /** - * comedi_bytes_per_scan() - Get length of asynchronous command "scan" in bytes + * comedi_bytes_per_scan_cmd() - Get length of asynchronous command "scan" in + * bytes * @s: COMEDI subdevice. + * @cmd: COMEDI command. * * Determines the overall scan length according to the subdevice type and the - * number of channels in the scan. + * number of channels in the scan for the specified command. * * For digital input, output or input/output subdevices, samples for * multiple channels are assumed to be packed into one or more unsigned @@ -408,9 +410,9 @@ EXPORT_SYMBOL_GPL(comedi_dio_update_state); * * Returns the overall scan length in bytes. */ -unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s) +unsigned int comedi_bytes_per_scan_cmd(struct comedi_subdevice *s, + struct comedi_cmd *cmd) { - struct comedi_cmd *cmd = &s->async->cmd; unsigned int num_samples; unsigned int bits_per_sample; @@ -427,6 +429,29 @@ unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s) } return comedi_samples_to_bytes(s, num_samples); } +EXPORT_SYMBOL_GPL(comedi_bytes_per_scan_cmd); + +/** + * comedi_bytes_per_scan() - Get length of asynchronous command "scan" in bytes + * @s: COMEDI subdevice. + * + * Determines the overall scan length according to the subdevice type and the + * number of channels in the scan for the current command. + * + * For digital input, output or input/output subdevices, samples for + * multiple channels are assumed to be packed into one or more unsigned + * short or unsigned int values according to the subdevice's %SDF_LSAMPL + * flag. For other types of subdevice, samples are assumed to occupy a + * whole unsigned short or unsigned int according to the %SDF_LSAMPL flag. + * + * Returns the overall scan length in bytes. + */ +unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s) +{ + struct comedi_cmd *cmd = &s->async->cmd; + + return comedi_bytes_per_scan_cmd(s, cmd); +} EXPORT_SYMBOL_GPL(comedi_bytes_per_scan); static unsigned int __comedi_nscans_left(struct comedi_subdevice *s, diff --git a/drivers/staging/comedi/drivers/ni_mio_common.c b/drivers/staging/comedi/drivers/ni_mio_common.c index 5edf59ac6706..b04dad8c7092 100644 --- a/drivers/staging/comedi/drivers/ni_mio_common.c +++ b/drivers/staging/comedi/drivers/ni_mio_common.c @@ -3545,6 +3545,7 @@ static int ni_cdio_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s, struct comedi_cmd *cmd) { struct ni_private *devpriv = dev->private; + unsigned int bytes_per_scan; int err = 0; /* Step 1 : check if triggers are trivially valid */ @@ -3579,9 +3580,12 @@ static int ni_cdio_cmdtest(struct comedi_device *dev, err |= comedi_check_trigger_arg_is(&cmd->convert_arg, 0); err |= comedi_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len); - err |= comedi_check_trigger_arg_max(&cmd->stop_arg, - s->async->prealloc_bufsz / - comedi_bytes_per_scan(s)); + bytes_per_scan = comedi_bytes_per_scan_cmd(s, cmd); + if (bytes_per_scan) { + err |= comedi_check_trigger_arg_max(&cmd->stop_arg, + s->async->prealloc_bufsz / + bytes_per_scan); + } if (err) return 3; -- 2.21.0