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=-19.4 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=unavailable 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 A0D5CC18E7B for ; Mon, 10 May 2021 12:37:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C4E2616E9 for ; Mon, 10 May 2021 12:37:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347398AbhEJMeA (ORCPT ); Mon, 10 May 2021 08:34:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:55450 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233404AbhEJLMD (ORCPT ); Mon, 10 May 2021 07:12:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id AB86E61941; Mon, 10 May 2021 11:09:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620644990; bh=2x17qympeKNR+HljtLITMAh+gayFVjXH0nYXirtyFrw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XZbqidngDKClfKoTcARmhOPdN/K0zrDKUNr/hcJC+lgGtJRc6cES1A2mZKqMx9IEd b8DsZlD5JMNipDb+4zdiXJC9iRSe482c3Lhrzlb9Bb7dDRrdH3sOTLhPSKKJUqyIBg aVrezuSDqikdu4cFTPgvp2bdnSKCrvxYHa6ZTjIE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lv Yunlong , Takashi Iwai Subject: [PATCH 5.12 271/384] ALSA: emu8000: Fix a use after free in snd_emu8000_create_mixer Date: Mon, 10 May 2021 12:21:00 +0200 Message-Id: <20210510102023.777227820@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210510102014.849075526@linuxfoundation.org> References: <20210510102014.849075526@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 @@ -1029,8 +1029,10 @@ 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;