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 42BC0C433F5 for ; Thu, 31 Mar 2022 09:32:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234004AbiCaJeT (ORCPT ); Thu, 31 Mar 2022 05:34:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234084AbiCaJeP (ORCPT ); Thu, 31 Mar 2022 05:34:15 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC4461BD99C; Thu, 31 Mar 2022 02:32:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1648719148; x=1680255148; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=ctf/hX3XkJggP7/+ZH5JrIfbFRaHucv2k5aVIYpgwkA=; b=HpkUKfvWAito1y1YpVTscD9KZN5HyjXNV/9dGDXloGZWhLmo5sdnvJXn vgBgE34X6lEqscgN8MLvRJt3gKcuoIS+E6pL4mWiFa3KpwTbD4ojS5OIL okXg5+an+5ORXtteFDfiwNysToGo8v7b7gp9zQK+GqoAZinYLQLRPXDSx olhmoA/xishw5PPOIB0uXeuD0ZUXxqzBFezRyTHTTc/zkJkwWhES6Hovf 1Id/LfZc57O/wv9edgnIdGY7IMzoJzka+hpgHRIaJao2KIz+TA7ljsX84 u6J167IiCeJfaHXHX/LuZQeKsMjA/5Koy7xcWEyN2awQbVjGS8AUytMvN w==; X-IronPort-AV: E=McAfee;i="6200,9189,10302"; a="259758101" X-IronPort-AV: E=Sophos;i="5.90,224,1643702400"; d="scan'208";a="259758101" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Mar 2022 02:32:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,224,1643702400"; d="scan'208";a="695424269" Received: from kuha.fi.intel.com ([10.237.72.185]) by fmsmga001.fm.intel.com with SMTP; 31 Mar 2022 02:32:25 -0700 Received: by kuha.fi.intel.com (sSMTP sendmail emulation); Thu, 31 Mar 2022 12:32:24 +0300 Date: Thu, 31 Mar 2022 12:32:24 +0300 From: Heikki Krogerus To: Greg KH Cc: Won Chung , Tomas Winkler , 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: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 31, 2022 at 11:00:46AM +0200, Greg KH wrote: > 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? A component is just a device that is declared to be a "component", and the code that declares it as component does not have to be the driver of that device. You simply can't assume that it's bind to a driver like this function does. In our case the "components" are USB ports, so devices that are never bind to drivers. thanks, -- heikki