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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 E323EC49ED7 for ; Fri, 20 Sep 2019 14:33:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1B9D2080F for ; Fri, 20 Sep 2019 14:33:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391567AbfITOdb (ORCPT ); Fri, 20 Sep 2019 10:33:31 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36352 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388242AbfITOZI (ORCPT ); Fri, 20 Sep 2019 10:25:08 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iBJqL-00051E-3D; Fri, 20 Sep 2019 15:25:05 +0100 Received: from ben by deadeye with local (Exim 4.92.1) (envelope-from ) id 1iBJqH-0007zp-SZ; Fri, 20 Sep 2019 15:25:01 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Ian Abbott" , "Greg Kroah-Hartman" Date: Fri, 20 Sep 2019 15:23:35 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 132/132] staging: comedi: dt282x: fix a null pointer deref on interrupt In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.74-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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: cfc_handle_events(dev, s_ao); [ Upstream equivalent: comedi_handle_events(dev, s_ao); -- IA ] 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.) Fixes: f21c74fa4cfe ("staging: comedi: dt282x: use cfc_handle_events()") Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- 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 @@ -483,7 +483,8 @@ static irqreturn_t dt282x_interrupt(int } #endif cfc_handle_events(dev, s); - cfc_handle_events(dev, s_ao); + if (s_ao) + cfc_handle_events(dev, s_ao); return IRQ_RETVAL(handled); }