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 176F7C433F5 for ; Thu, 31 Mar 2022 09:13:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233656AbiCaJOq (ORCPT ); Thu, 31 Mar 2022 05:14:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233645AbiCaJOo (ORCPT ); Thu, 31 Mar 2022 05:14:44 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E02251F89D0; Thu, 31 Mar 2022 02:12:56 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 9FEBF1F869; Thu, 31 Mar 2022 09:12:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1648717975; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=kcFvM9YBZ68bJuJVpDcgIHN0wJM9eIxb2o15OLRqjQc=; b=HhLJxKebAW2IF9RMMbxWL4B/lNzyYOr/6pyCLw6flAeFb/psb2HrEUGpmGbgOQ52fs1DN2 2wK4n0JWq+gWRvLNeDyVu0+jZox/bUMDWpFMkXwoztkgx028AiRd4/Bmp1rKAeViieYMAe c1ZSlkcFVKuerWwDNEiuS/+pSECCVng= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1648717975; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=kcFvM9YBZ68bJuJVpDcgIHN0wJM9eIxb2o15OLRqjQc=; b=PWtysn1jZfQ5GJ8mCL57Z2TrRj+yKDje9oub00sloCxsSi7mEZPoJ9dyz46K6Y/Cc0MWUH VC5io5pJELx0LFCw== Received: from alsa1.suse.de (alsa1.suse.de [10.160.4.42]) by relay2.suse.de (Postfix) with ESMTP id 898D9A3B87; Thu, 31 Mar 2022 09:12:55 +0000 (UTC) Date: Thu, 31 Mar 2022 11:12:55 +0200 Message-ID: From: Takashi Iwai To: Won Chung Cc: Takashi Iwai , Jaroslav Kysela , Takashi Iwai , Heikki Krogerus , Mika Westerberg , Benson Leung , Prashant Malani , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] sound/hda: Add NULL check to component match callback function In-Reply-To: References: <20220330211913.2068108-1-wonchung@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 31 Mar 2022 10:38:34 +0200, Won Chung wrote: > > On Thu, Mar 31, 2022 at 12:27 AM Takashi Iwai wrote: > > > > On Wed, 30 Mar 2022 23:19:13 +0200, > > Won Chung wrote: > > > > > > Component match callback function needs to check if expected data is > > > passed to it. 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. > > > > > > Fixes: 7b882fe3e3e8b ("ALSA: hda - handle multiple i915 device instances") > > > Signed-off-by: Heikki Krogerus > > > Signed-off-by: Mika Westerberg > > > Signed-off-by: Won Chung > > > --- > > > - Add "Fixes" tag > > > - Send to stable@vger.kernel.org > > > > You rather need to add "Cc: stable@vger.kernel.org" line to the patch > > itself (around sign-off block), not actually Cc'ing the mail. > > I edited manually, but please do it so at the next time. > > > > Although I applied the patch as-is now, I wonder... > > > > > > > - if (!strcmp(dev->driver->name, "i915") && > > > + if (dev->driver && !strcmp(dev->driver->name, "i915") && > > > > Can NULL dev->driver be really seen? I thought the components are > > added by the drivers, hence they ought to have the driver field set. > > But there can be corner cases I overlooked. > > > > > > thanks, > > > > Takashi > > Hi Takashi, > > When I try using component_add in a different driver (usb4 in my > case), I think dev->driver here is NULL because the i915 drivers do > not have their component master fully bound when this new component is > registered. When I test it, it seems to be causing a crash. Hm, from where component_add*() is called? Basically dev->driver must be already set before the corresponding driver gets bound at __driver_probe_deviec(). So, if the device is added to component from the corresponding driver's probe, dev->driver must be non-NULL. > Would it be okay for me to resend a new patch with the flags > corrected? I have mistakenly added Heikki and Mika as "Signed-off-by" > instead of "Suggested-by". I am sorry for that. Ah that's bad. I'll reset the branch, then. Please resubmit properly. thanks, Takashi