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 1705DC001DC for ; Mon, 24 Jul 2023 01:46:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232682AbjGXBqy (ORCPT ); Sun, 23 Jul 2023 21:46:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48388 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232525AbjGXBpg (ORCPT ); Sun, 23 Jul 2023 21:45:36 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C26D3B9; Sun, 23 Jul 2023 18:39:15 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 85A6060F98; Mon, 24 Jul 2023 01:34:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10D6CC433CC; Mon, 24 Jul 2023 01:34:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690162463; bh=omSorsWROY2XhObA/P2khsZpOVC+P+TZxcFELmq9keA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UMeiGuXPWkB7TQ8wCqeW7F0qM8iUrDtfuHJmI+8sTyc18peBhzKrWRT7ubErmVseh QqX6hpT9BlvyrHoQAQwN4+JqoxSNEAvRJTHnebvVn2FKjrmRLF/1cH/cMZwUvAX3KU uJwDF4syrT3yQa7MCgC+7A98bbz42PhjqfQrzMU7N1+Uty85+1Oaxh7psGwpoVKQCU MD5c+ipTwMFzNK/4cNemCDCrr2aGC9Ht66iXSuUE0jsk92GNH1ILhI5fG5qIsHZclL frayJbKl2vSj53rJXVaCMgTfKQi8T4DOrvPM9WZsO5Gwz0PSZpnMXBE/oXqwT4nuf1 Mv4QHXfRyMYtQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Tuo Li , BassCheck , Takashi Iwai , Sasha Levin , perex@perex.cz, tiwai@suse.com, alsa-devel@alsa-project.org Subject: [PATCH AUTOSEL 5.10 15/16] ALSA: hda: fix a possible null-pointer dereference due to data race in snd_hdac_regmap_sync() Date: Sun, 23 Jul 2023 21:33:59 -0400 Message-Id: <20230724013401.2333159-15-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230724013401.2333159-1-sashal@kernel.org> References: <20230724013401.2333159-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.10.186 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tuo Li [ Upstream commit 1f4a08fed450db87fbb5ff5105354158bdbe1a22 ] The variable codec->regmap is often protected by the lock codec->regmap_lock when is accessed. However, it is accessed without holding the lock when is accessed in snd_hdac_regmap_sync(): if (codec->regmap) In my opinion, this may be a harmful race, because if codec->regmap is set to NULL right after the condition is checked, a null-pointer dereference can occur in the called function regcache_sync(): map->lock(map->lock_arg); --> Line 360 in drivers/base/regmap/regcache.c To fix this possible null-pointer dereference caused by data race, the mutex_lock coverage is extended to protect the if statement as well as the function call to regcache_sync(). [ Note: the lack of the regmap_lock itself is harmless for the current codec driver implementations, as snd_hdac_regmap_sync() is only for PM runtime resume that is prohibited during the codec probe. But the change makes the whole code more consistent, so it's merged as is -- tiwai ] Reported-by: BassCheck Signed-off-by: Tuo Li Link: https://lore.kernel.org/r/20230703031016.1184711-1-islituo@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/hda/hdac_regmap.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/sound/hda/hdac_regmap.c b/sound/hda/hdac_regmap.c index d75f31eb9d78f..bf35acca5ea0e 100644 --- a/sound/hda/hdac_regmap.c +++ b/sound/hda/hdac_regmap.c @@ -597,10 +597,9 @@ EXPORT_SYMBOL_GPL(snd_hdac_regmap_update_raw_once); */ void snd_hdac_regmap_sync(struct hdac_device *codec) { - if (codec->regmap) { - mutex_lock(&codec->regmap_lock); + mutex_lock(&codec->regmap_lock); + if (codec->regmap) regcache_sync(codec->regmap); - mutex_unlock(&codec->regmap_lock); - } + mutex_unlock(&codec->regmap_lock); } EXPORT_SYMBOL_GPL(snd_hdac_regmap_sync); -- 2.39.2