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=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 55644C76192 for ; Thu, 18 Jul 2019 03:16:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 21A7021855 for ; Thu, 18 Jul 2019 03:16:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563419816; bh=Oe/yRIXP5akfgOnAVcmqiPsHio/RgupjUp5hy5Woa48=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=08hD1Wov8JGaMsuAdJEidzHiA32Izlz65twb9gw65UElRx1/dIEuKJ6KyN+GqxGeG MmTCYEMTySo8Cq8eKgrYzFR9acGsVWFlQ4RbvDSAH6Q2yah3ncNZCYF0yUmiBiPB59 rtmFuu3HZ9hmeP07R7M4iOAJnuNJ4+vWSZbBVEX0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729855AbfGRDPD (ORCPT ); Wed, 17 Jul 2019 23:15:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:51650 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391594AbfGRDPC (ORCPT ); Wed, 17 Jul 2019 23:15:02 -0400 Received: from localhost (115.42.148.210.bf.2iij.net [210.148.42.115]) (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 0697D2173E; Thu, 18 Jul 2019 03:15:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563419701; bh=Oe/yRIXP5akfgOnAVcmqiPsHio/RgupjUp5hy5Woa48=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oPbtWSFYLm0juNgB48BRLWjbytGxtd89Fkt873MYHaM/WEVAkNtxisJRYnCfPek6Y CE1ao6KwABq416f4OZE8AfxVmP51Jg5R+RgvIzu5xwlfEOi8rc6Me5NMvbG9+w6W3R Lt86St22Sn3SeScMO1rlfP0wnqxzl5kqxSzUIz0A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ian Abbott Subject: [PATCH 4.4 23/40] staging: comedi: dt282x: fix a null pointer deref on interrupt Date: Thu, 18 Jul 2019 12:02:19 +0900 Message-Id: <20190718030048.304154058@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190718030039.676518610@linuxfoundation.org> References: <20190718030039.676518610@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 @@ -553,7 +553,8 @@ 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); }