From patchwork Thu May 20 09:17:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 444518 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham 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 03410C433ED for ; Thu, 20 May 2021 09:44:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D89CF613D8 for ; Thu, 20 May 2021 09:44:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233698AbhETJqK (ORCPT ); Thu, 20 May 2021 05:46:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:47556 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233716AbhETJoJ (ORCPT ); Thu, 20 May 2021 05:44:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C2E00613F1; Thu, 20 May 2021 09:33:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621503186; bh=AL7u/WMym1lYfDxy4MVtqLMV/bv2ffPUd+7yZssaMYs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MSewxJmuwKO2gVxFJxwAgGycw7HTL68EmENDvzR2Thb72pZVuIDAVlMKKjCxbcooL VLXxtAiYAB5YPv6xpR6Zg18B78zqThigf37PEtOFjJcKwUcSwBccfgSHRGGcqWRdAy 7sUyvsa/Px8bTEuaYmj7KX2UqyvdoJIM3cP9xEJ0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lv Yunlong , Takashi Iwai Subject: [PATCH 4.19 074/425] ALSA: emu8000: Fix a use after free in snd_emu8000_create_mixer Date: Thu, 20 May 2021 11:17:23 +0200 Message-Id: <20210520092133.883131794@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092131.308959589@linuxfoundation.org> References: <20210520092131.308959589@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Lv Yunlong commit 1c98f574403dbcf2eb832d5535a10d967333ef2d upstream. Our code analyzer reported a uaf. In snd_emu8000_create_mixer, the callee snd_ctl_add(..,emu->controls[i]) calls snd_ctl_add_replace(.., kcontrol,..). Inside snd_ctl_add_replace(), if error happens, kcontrol will be freed by snd_ctl_free_one(kcontrol). Then emu->controls[i] points to a freed memory, and the execution comes to __error branch of snd_emu8000_create_mixer. The freed emu->controls[i] is used in snd_ctl_remove(card, emu->controls[i]). My patch set emu->controls[i] to NULL if snd_ctl_add() failed to avoid the uaf. Signed-off-by: Lv Yunlong Cc: Link: https://lore.kernel.org/r/20210426131129.4796-1-lyl2019@mail.ustc.edu.cn Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/isa/sb/emu8000.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/sound/isa/sb/emu8000.c +++ b/sound/isa/sb/emu8000.c @@ -1042,8 +1042,10 @@ snd_emu8000_create_mixer(struct snd_card memset(emu->controls, 0, sizeof(emu->controls)); for (i = 0; i < EMU8000_NUM_CONTROLS; i++) { - if ((err = snd_ctl_add(card, emu->controls[i] = snd_ctl_new1(mixer_defs[i], emu))) < 0) + if ((err = snd_ctl_add(card, emu->controls[i] = snd_ctl_new1(mixer_defs[i], emu))) < 0) { + emu->controls[i] = NULL; goto __error; + } } return 0;