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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 810A9C433E0 for ; Mon, 10 Aug 2020 17:29:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4A3562083B for ; Mon, 10 Aug 2020 17:29:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597080567; bh=ireM7xLApekHQIqjELsBbT2kJiFJu4rDCIUy4AvUv8Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=BKzvc6ZixtRpfiH0QBsaknoAceCzeZLme5UQh4Dg2UymfbvbOHS47UJ9Xl0Ttln8b o9yH8G4n9Txn5vyhIdV97xRwhZ3DBgQiSgGAPHw60tE8BxOCY+bGs18GYlByjoCjLm QrlJO6G1ee/FkqBtKht0qxeCmNyOl4JBGlL9aoQQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727003AbgHJR31 (ORCPT ); Mon, 10 Aug 2020 13:29:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:57456 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725862AbgHJR30 (ORCPT ); Mon, 10 Aug 2020 13:29:26 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 97E6520838; Mon, 10 Aug 2020 17:29:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597080566; bh=ireM7xLApekHQIqjELsBbT2kJiFJu4rDCIUy4AvUv8Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=F1tDgPKQ8a48L6iXeXl2ZQ+CV+co/rlaBWrRB5CIyCCdJto7kYTEFdNv49K9N/9Y5 rDuTX5EDazzaDQZWo494zj8Tk+rfGv8PkWAewnuz3/NtHw2HCOORQb1SpdmA8Xqp8n T9Dz72HdKHAoAsEM2uS2KfzOnSyOz07eKsKy3tjA= Date: Mon, 10 Aug 2020 19:29:36 +0200 From: Greg Kroah-Hartman To: Pavel Machek Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+1a54a94bd32716796edd@syzkaller.appspotmail.com, syzbot+9d2abfef257f3e2d4713@syzkaller.appspotmail.com, Hillf Danton , Takashi Iwai Subject: Re: [PATCH 4.19 06/48] ALSA: seq: oss: Serialize ioctls Message-ID: <20200810172936.GA82601@kroah.com> References: <20200810151804.199494191@linuxfoundation.org> <20200810151804.528955642@linuxfoundation.org> <20200810163717.GA24408@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200810163717.GA24408@amd> Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Aug 10, 2020 at 06:37:17PM +0200, Pavel Machek wrote: > Hi! > > > commit 80982c7e834e5d4e325b6ce33757012ecafdf0bb upstream. > > > > Some ioctls via OSS sequencer API may race and lead to UAF when the > > port create and delete are performed concurrently, as spotted by a > > couple of syzkaller cases. This patch is an attempt to address it by > > serializing the ioctls with the existing register_mutex. > > > > Basically OSS sequencer API is an obsoleted interface and was designed > > without much consideration of the concurrency. There are very few > > applications with it, and the concurrent performance isn't asked, > > hence this "big hammer" approach should be good enough. > > That really is a "big hammer". And I believe it is too big. Please discuss code architecture decisions on the mailing list for the subsystem/patch. Doing it in random stable backports does not help out as all of the developers involved are not copied here. thanks, greg k-h