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=-5.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 D8528C2B9F4 for ; Tue, 22 Jun 2021 07:45:59 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1EE0A6128E for ; Tue, 22 Jun 2021 07:45:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1EE0A6128E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=b4.vu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id EABC286F; Tue, 22 Jun 2021 09:45:04 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz EABC286F DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1624347955; bh=RUJIDZGnns9jY0ORfp2RNmHm1iCTDcERk5lqXSg5t2c=; h=Date:From:To:Subject:References:In-Reply-To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=M0WtmhYZVJKV9D7zI/pEeqp+m74vIkBmnmQuTB9JvuQDzkeS6HC1vYiiqxVUl5mR+ rwgti/+7bSq6IlS/KNnBNCb77KZxiyEcbaZvyWRZK+zajmxQz5GscqMFGdT3JAps/T 34CHl7KNRoAGzOHht8jnziYiL5GOaRj+Gye40lOo= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 7A91BF80137; Tue, 22 Jun 2021 09:45:04 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 80A45F80268; Tue, 22 Jun 2021 09:45:02 +0200 (CEST) Received: from m.b4.vu (m.b4.vu [203.16.231.148]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 1A393F80137 for ; Tue, 22 Jun 2021 09:44:58 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 1A393F80137 Received: by m.b4.vu (Postfix, from userid 1000) id 4797061E2853; Tue, 22 Jun 2021 17:14:54 +0930 (ACST) Date: Tue, 22 Jun 2021 17:14:54 +0930 From: "Geoffrey D. Bennett" To: Takashi Iwai Subject: Re: [PATCH 16/31] ALSA: usb-audio: scarlett2: Add Gen 3 mixer support Message-ID: <20210622074454.GB13614@m.b4.vu> References: <0b00f3a5-fe31-0ad5-c723-d354dc724e58@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Cc: Hin-Tak Leung , alsa-devel@alsa-project.org, Vladimir Sadovnikov X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Tue, Jun 22, 2021 at 09:34:25AM +0200, Takashi Iwai wrote: > On Tue, 22 Jun 2021 09:07:20 +0200, > Vladimir Sadovnikov wrote: > > > > Hello Takashi! > > > > Since Focusrite devices are too advanced in settings, the overall > > amount of 256 controls is not enough for these devices (like 18i20). > > I would like also to extend this constant up to 1024 or even more > > since adding support of software configuration of the device also > > can exceed the amount of 512 control elements. > > This define isn't for the total number of mixer elements. Instead, > it's just a size of the bitmap table that contains the head of the > linked list for each unit id (in the sense of USB mixer spec). > So the number of mixer elements is unlimited. Sorry I don't understand what's going on then. Am I calling snd_usb_mixer_add_control() wrong? Because when I called it more than MAX_ID_ELEMS times I got a buffer overflow in mixer->id_elems[] (from memory, I can confirm tonight). snd_usb_create_mixer() has: mixer->id_elems = kcalloc(MAX_ID_ELEMS, sizeof(*mixer->id_elems), GFP_KERNEL); snd_usb_mixer_add_control() called from mixer_scarlett_gen2.c ends up at snd_usb_mixer_add_list() which does: list->next_id_elem = mixer->id_elems[list->id]; mixer->id_elems[list->id] = list; And list->id was going over MAX_ID_ELEMS.