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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 DAE99C742BA for ; Fri, 12 Jul 2019 12:33:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B183121019 for ; Fri, 12 Jul 2019 12:33:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562934812; bh=t5280lZFvII97lEhHEy/0FVCtgfXs0UW8Pa4O96y/hI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JF3qrWhbqlHYWVJNAe6pGkRXkKG0azhjczbx+X/gH8hZgN47LDQnxrPhxJM7vgv+s Ip41OfUjb9vasmHLOag9oVwyHf0XepNN0q9e7RSYqQ5VgTrB2JVJ2BeriXVfnTKagS jGT7RQ7o3JdBLLoFqtnIHpcP5GUtsaMZ/C41Ga4s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729606AbfGLMd0 (ORCPT ); Fri, 12 Jul 2019 08:33:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:52572 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729208AbfGLMdZ (ORCPT ); Fri, 12 Jul 2019 08:33:25 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.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 458DF216C4; Fri, 12 Jul 2019 12:33:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562934804; bh=t5280lZFvII97lEhHEy/0FVCtgfXs0UW8Pa4O96y/hI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U/XjRu3BhRa+eGL0FBQaUUekgzX61sWlJVHhLGKoANuamW78mL9jpkbZwp7K6ZjpA fqTWDV/9ejFDKZofR9CpGxcAOHcH6yJoX0e2eQW8vmRFuTjTVRomglsYSO/Jq6mhT/ EE5mXEwHdIh2YUjQlak0TyRHBqHXjGJ9l6JbZLC8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ian Abbott Subject: [PATCH 5.2 35/61] staging: comedi: dt282x: fix a null pointer deref on interrupt Date: Fri, 12 Jul 2019 14:19:48 +0200 Message-Id: <20190712121622.493069211@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190712121620.632595223@linuxfoundation.org> References: <20190712121620.632595223@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Ian Abbott commit b8336be66dec06bef518030a0df9847122053ec5 upstream. The interrupt handler `dt282x_interrupt()` causes a null pointer dereference for those supported boards that have no analog output support. For these boards, `dev->write_subdev` will be `NULL` and therefore the `s_ao` subdevice pointer variable will be `NULL`. In that case, the following call near the end of the interrupt handler results in a null pointer dereference: comedi_handle_events(dev, s_ao); Fix it by only calling the above function if `s_ao` is valid. (There are other uses of `s_ao` by the interrupt handler that may or may not be reached depending on values of hardware registers. Trust that they are reliable for now.) Note: commit 4f6f009b204f ("staging: comedi: dt282x: use comedi_handle_events()") propagates an earlier error from commit f21c74fa4cfe ("staging: comedi: dt282x: use cfc_handle_events()"). Fixes: 4f6f009b204f ("staging: comedi: dt282x: use comedi_handle_events()") Cc: # v3.19+ Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/dt282x.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/staging/comedi/drivers/dt282x.c +++ b/drivers/staging/comedi/drivers/dt282x.c @@ -557,7 +557,8 @@ static irqreturn_t dt282x_interrupt(int } #endif comedi_handle_events(dev, s); - comedi_handle_events(dev, s_ao); + if (s_ao) + comedi_handle_events(dev, s_ao); return IRQ_RETVAL(handled); }