Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759894AbaJ3MnH (ORCPT ); Thu, 30 Oct 2014 08:43:07 -0400 Received: from smtp89.iad3a.emailsrvr.com ([173.203.187.89]:54300 "EHLO smtp89.iad3a.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759871AbaJ3MnE (ORCPT ); Thu, 30 Oct 2014 08:43:04 -0400 X-Sender-Id: abbotti@mev.co.uk From: Ian Abbott To: Cc: Greg Kroah-Hartman , Ian Abbott , H Hartley Sweeten , Subject: [PATCH 4/7] staging: comedi: don't allow read() on async command set up for "write" Date: Thu, 30 Oct 2014 12:42:29 +0000 Message-Id: <1414672952-1587-5-git-send-email-abbotti@mev.co.uk> X-Mailer: git-send-email 2.1.1 In-Reply-To: <1414672952-1587-1-git-send-email-abbotti@mev.co.uk> References: <1414672952-1587-1-git-send-email-abbotti@mev.co.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a Comedi asynchronous command has been set up for data transfer in the "write" direction on the current "read" subdevice (for those subdevices that support both directions), don't allow the "read" file operation as that would mess with the data in the comedi data buffer that is read by the low-level comedi hardware driver. Signed-off-by: Ian Abbott --- drivers/staging/comedi/comedi_fops.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index fef68da..6805ec9 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -2210,6 +2210,10 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes, retval = -EACCES; goto out; } + if (async->cmd.flags & CMDF_WRITE) { + retval = -EINVAL; + goto out; + } add_wait_queue(&async->wait_head, &wait); while (nbytes > 0 && !retval) { @@ -2249,6 +2253,10 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes, retval = -EACCES; break; } + if (async->cmd.flags & CMDF_WRITE) { + retval = -EINVAL; + break; + } continue; } m = copy_to_user(buf, async->prealloc_buf + -- 2.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/