From patchwork Thu Apr 14 18:31:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nirmoy Das X-Patchwork-Id: 12813962 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 37097C4332F for ; Thu, 14 Apr 2022 19:29:31 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7683210E2B4; Thu, 14 Apr 2022 19:29:30 +0000 (UTC) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTPS id 84AD910E230 for ; Thu, 14 Apr 2022 19:29:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1649964568; x=1681500568; h=from:to:subject:date:message-id:in-reply-to:references: mime-version:content-transfer-encoding; bh=f1RtptW/eB+VXD/uy/33txufQYgO9SsgPC8EVo1NPIE=; b=VjeIUqILU7zIdUVx5ZhnuLGM4GBeHUpgRnn+QfHv2Gpt501nrOFX1Gx+ BPEO4R4Zfyuk+LZBsEdIDYBI8JEYdm3VFhlinhuDHwWS1R89/coK5Xyx5 19uMTPixDoKA4h2J1tE4qamyBFaSdm/JbE6PHYsYckDBE/edxShJUVGft +sjupswAT1Uu+GI4B9ulGDEfpgk/XtWTN817HHUpyJT6ipgWL/bFyqh36 U9DHifarwh7uk5Y0V7Nc56e/UEVx2YN6GRQNdaLtk4iZd3NDevo3nhdn7 WtidvBvRyWjXRIeGzXioa7xZas277UDrpCUet4sYLXIjbWtGUa79zsvD6 A==; X-IronPort-AV: E=McAfee;i="6400,9594,10317"; a="263191996" X-IronPort-AV: E=Sophos;i="5.90,260,1643702400"; d="scan'208";a="263191996" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Apr 2022 12:29:28 -0700 X-IronPort-AV: E=Sophos;i="5.90,260,1643702400"; d="scan'208";a="573960182" Received: from nirmoyda-desk.igk.intel.com ([10.102.13.19]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Apr 2022 12:29:27 -0700 From: Nirmoy Das To: intel-gfx@lists.freedesktop.org Date: Thu, 14 Apr 2022 20:31:46 +0200 Message-Id: <20220414183148.15884-2-nirmoy.das@intel.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220414183148.15884-1-nirmoy.das@intel.com> References: <20220414183148.15884-1-nirmoy.das@intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 1/2] ALSA: core: Add snd_card_free_on_error() helper X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" From: Takashi Iwai This is a small helper function to handle the error path more easily when an error happens during the probe for the device with the device-managed card. Since devres releases in the reverser order of the creations, usually snd_card_free() gets called at the last in the probe error path unless it already reached snd_card_register() calls. Due to this nature, when a driver expects the resource releases in card->private_free, this might be called too lately. As a workaround, one should call the probe like: static int __some_probe(...) { // do real probe.... } static int some_probe(...) { return snd_card_free_on_error(dev, __some_probe(dev, ...)); } so that the snd_card_free() is called explicitly at the beginning of the error path from the probe. This function will be used in the upcoming fixes to address the regressions by devres usages. Fixes: e8ad415b7a55 ("ALSA: core: Add managed card creation") Cc: Link: https://lore.kernel.org/r/20220412093141.8008-2-tiwai@suse.de Signed-off-by: Takashi Iwai --- include/sound/core.h | 1 + sound/core/init.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/include/sound/core.h b/include/sound/core.h index b7e9b58d3c78..6d4cc49584c6 100644 --- a/include/sound/core.h +++ b/include/sound/core.h @@ -284,6 +284,7 @@ int snd_card_disconnect(struct snd_card *card); void snd_card_disconnect_sync(struct snd_card *card); int snd_card_free(struct snd_card *card); int snd_card_free_when_closed(struct snd_card *card); +int snd_card_free_on_error(struct device *dev, int ret); void snd_card_set_id(struct snd_card *card, const char *id); int snd_card_register(struct snd_card *card); int snd_card_info_init(void); diff --git a/sound/core/init.c b/sound/core/init.c index 31ba7024e3ad..726a8353201f 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -209,6 +209,12 @@ static void __snd_card_release(struct device *dev, void *data) * snd_card_register(), the very first devres action to call snd_card_free() * is added automatically. In that way, the resource disconnection is assured * at first, then released in the expected order. + * + * If an error happens at the probe before snd_card_register() is called and + * there have been other devres resources, you'd need to free the card manually + * via snd_card_free() call in the error; otherwise it may lead to UAF due to + * devres call orders. You can use snd_card_free_on_error() helper for + * handling it more easily. */ int snd_devm_card_new(struct device *parent, int idx, const char *xid, struct module *module, size_t extra_size, @@ -235,6 +241,28 @@ int snd_devm_card_new(struct device *parent, int idx, const char *xid, } EXPORT_SYMBOL_GPL(snd_devm_card_new); +/** + * snd_card_free_on_error - a small helper for handling devm probe errors + * @dev: the managed device object + * @ret: the return code from the probe callback + * + * This function handles the explicit snd_card_free() call at the error from + * the probe callback. It's just a small helper for simplifying the error + * handling with the managed devices. + */ +int snd_card_free_on_error(struct device *dev, int ret) +{ + struct snd_card *card; + + if (!ret) + return 0; + card = devres_find(dev, __snd_card_release, NULL, NULL); + if (card) + snd_card_free(card); + return ret; +} +EXPORT_SYMBOL_GPL(snd_card_free_on_error); + static int snd_card_init(struct snd_card *card, struct device *parent, int idx, const char *xid, struct module *module, size_t extra_size)