From patchwork Thu May 20 09:20:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 444171 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 579A8C43470 for ; Thu, 20 May 2021 10:49:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FCDB61019 for ; Thu, 20 May 2021 10:49:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237766AbhETKvF (ORCPT ); Thu, 20 May 2021 06:51:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:47942 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237589AbhETKsW (ORCPT ); Thu, 20 May 2021 06:48:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2D9F661411; Thu, 20 May 2021 09:58:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621504714; bh=AL7u/WMym1lYfDxy4MVtqLMV/bv2ffPUd+7yZssaMYs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0jQDLfDuhexHRxqDmBSI6oOZCwQi2od3HIo2ZA5gd9ykCVpJx+j9fxZYsEyVkIIC5 xBtCgQ2iyF9/CNaXF3xMLw30BQUu8Vl/+dHywrlDRMb6i7ng+zGnhHxgKhZDaMUo/n mDq3UPN9fVCz327gQ25RjjlxXhhHMWfp3+mUaspI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lv Yunlong , Takashi Iwai Subject: [PATCH 4.9 048/240] ALSA: emu8000: Fix a use after free in snd_emu8000_create_mixer Date: Thu, 20 May 2021 11:20:40 +0200 Message-Id: <20210520092110.282103267@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092108.587553970@linuxfoundation.org> References: <20210520092108.587553970@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;