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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 383CEC433FE for ; Thu, 31 Mar 2022 09:01:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233489AbiCaJCu (ORCPT ); Thu, 31 Mar 2022 05:02:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233434AbiCaJCo (ORCPT ); Thu, 31 Mar 2022 05:02:44 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C88051585; Thu, 31 Mar 2022 02:00:56 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 3EFC4B82000; Thu, 31 Mar 2022 09:00:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7AF93C340ED; Thu, 31 Mar 2022 09:00:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1648717253; bh=wNwVnTnwlRKd3pJ0yCmXSRbxpRcvTX29e7Vo18OTPDU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sDrtMRinc/Io8nwpaMAlnKMwo7KOwwzcQZtzCTP0gXme0LJrstd7O6KZAlIc/V1qK O6bDp0AX0GKRl7ZClO1pDz0aftDdiWPqyS5WeH1XysqeQPDpoKj2LFoUAiXF4jM1Fy xPtyc4mVxczZYluNFs5AqQFlzhuyV5c6I1kqUlTU= Date: Thu, 31 Mar 2022 11:00:46 +0200 From: Greg KH To: Won Chung Cc: Tomas Winkler , Heikki Krogerus , Mika Westerberg , Benson Leung , Prashant Malani , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3] misc/mei: Add NULL check to component match callback functions Message-ID: References: <20220331084918.2592699-1-wonchung@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220331084918.2592699-1-wonchung@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 31, 2022 at 08:49:18AM +0000, Won Chung wrote: > Component match callback functions need to check if expected data is > passed to them. Without this check, it can cause a NULL pointer > dereference when another driver registers a component before i915 > drivers have their component master fully bind. How can that happen in a real system? Or does this just happen for when you are doing development and testing? > > Fixes: 1e8d19d9b0dfc ("mei: hdcp: bind only with i915 on the same PCH") > Fixes: c2004ce99ed73 ("mei: pxp: export pavp client to me client bus") > Suggested-by: Heikki Krogerus > Suggested-by: Mika Westerberg > Signed-off-by: Won Chung > Cc: stable@vger.kernel.org Why does this need to go to stable? How can this be triggered in older kernels? > --- > Changes from v2: > - Correctly add "Suggested-by" tag > - Add "Cc: stable@vger.kernel.org" > > Changes from v1: > - Add "Fixes" tag > - Send to stable@vger.kernel.org > > drivers/misc/mei/hdcp/mei_hdcp.c | 2 +- > drivers/misc/mei/pxp/mei_pxp.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c b/drivers/misc/mei/hdcp/mei_hdcp.c > index ec2a4fce8581..843dbc2b21b1 100644 > --- a/drivers/misc/mei/hdcp/mei_hdcp.c > +++ b/drivers/misc/mei/hdcp/mei_hdcp.c > @@ -784,7 +784,7 @@ static int mei_hdcp_component_match(struct device *dev, int subcomponent, > { > struct device *base = data; > > - if (strcmp(dev->driver->name, "i915") || > + if (!base || !dev->driver || strcmp(dev->driver->name, "i915") || How can base be NULL? > subcomponent != I915_COMPONENT_HDCP) > return 0; > > diff --git a/drivers/misc/mei/pxp/mei_pxp.c b/drivers/misc/mei/pxp/mei_pxp.c > index f7380d387bab..e32a81da8af6 100644 > --- a/drivers/misc/mei/pxp/mei_pxp.c > +++ b/drivers/misc/mei/pxp/mei_pxp.c > @@ -131,7 +131,7 @@ static int mei_pxp_component_match(struct device *dev, int subcomponent, > { > struct device *base = data; > > - if (strcmp(dev->driver->name, "i915") || > + if (!base || !dev->driver || strcmp(dev->driver->name, "i915") || Same here, shouldn't this be caught by the driver core or bus and match should not be called? Why not fix this in the component/driver core instead? thanks, greg k-h