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 BA0D9C742B9 for ; Fri, 12 Jul 2019 12:23:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 949E2216FD for ; Fri, 12 Jul 2019 12:23:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562934234; bh=t5280lZFvII97lEhHEy/0FVCtgfXs0UW8Pa4O96y/hI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=eWwnCyyhc5vwGd8Kbm/1OWId5sUGezP/gmIqgOG62w08lTXuEGImfCU9I6kb8Di0S FhRUsgfviu6tV/xR+qbJO34mVQIJgW73uNUQQpZ386T+qXPZ6u/JMk5lpSbvabLwlk MAaDHGW/u8wpDwrELs1KKzpfmH9lQeF9IbOt60fk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727995AbfGLMXw (ORCPT ); Fri, 12 Jul 2019 08:23:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:59968 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727991AbfGLMXv (ORCPT ); Fri, 12 Jul 2019 08:23:51 -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 81D2A216E3; Fri, 12 Jul 2019 12:23:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562934231; bh=t5280lZFvII97lEhHEy/0FVCtgfXs0UW8Pa4O96y/hI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=R83u+4c+KrbQk0CCS3rCU18V3LAD3UVTtQb6I6nEnPYpcArFIVqAF4jwV8OmfpqD5 iikatL381LlJaPz3cwTIrVJ7UaXrx7/i2r9WPyCYgCAf+rdAKl4AqJDZOQbWpNK1rZ 7gDsPn4MddU5uypHQFJUyOqZp1PdN4ixQogDO3Z8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ian Abbott Subject: [PATCH 4.19 78/91] staging: comedi: dt282x: fix a null pointer deref on interrupt Date: Fri, 12 Jul 2019 14:19:21 +0200 Message-Id: <20190712121625.991361986@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190712121621.422224300@linuxfoundation.org> References: <20190712121621.422224300@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); }