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=-0.8 required=3.0 tests=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 3EEFEC433DF for ; Mon, 18 May 2020 23:41:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F290207D4 for ; Mon, 18 May 2020 23:41:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="Gx65fZNs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727938AbgERXlm (ORCPT ); Mon, 18 May 2020 19:41:42 -0400 Received: from wout3-smtp.messagingengine.com ([64.147.123.19]:40883 "EHLO wout3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726407AbgERXll (ORCPT ); Mon, 18 May 2020 19:41:41 -0400 Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.west.internal (Postfix) with ESMTP id 35437AF9; Mon, 18 May 2020 19:41:40 -0400 (EDT) Received: from imap10 ([10.202.2.60]) by compute1.internal (MEProxy); Mon, 18 May 2020 19:41:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=J1AR48 /Bqor8PSknA+RS5/aKkcT8MxVKSlgexmnnodk=; b=Gx65fZNsPlulb/wmjgwQnn gTP7oNnJH22elYHhP4vVlNG7ccXkIQyVb0dO68AWobSWeIXSVk01mtfdBPJaBWNB amvxrJRWZn95E8xxn6Nzh7V5MdbYcD7qRGXRioxa1iFVNPskAMp4oTCQHvYWPsB9 9F3pOa6ovJkUjuLLOqGBZmp9ozwqPbkIl3OOUx09+us5KdyAIiEzaXSLKliHv7TU Q7zt4wVhUQ10Fgkv5iRrM+aSE1DDdII11dRqm1PX0ZDUTz8cmY9bzHFBJB1h6ErY AswrTuTZSbpj5rYaeTXrteVC4WnSDtlx5WnKYzAN9fvnq5/Gn8BFcHATqWPkvzHA == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduhedruddtiedgvdegucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepofgfggfkjghffffhvffutgesthdtredtreertdenucfhrhhomhepfdevohhl ihhnucghrghlthgvrhhsfdcuoeifrghlthgvrhhssehvvghrsghumhdrohhrgheqnecugg ftrfgrthhtvghrnhepheegheehieeludegleelteekieejheeuteetgefgiedvkedugefh hfeuffelvddvnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrh homhepfigrlhhtvghrshesvhgvrhgsuhhmrdhorhhg X-ME-Proxy: Received: by mailuser.nyi.internal (Postfix, from userid 501) id 421B62005D; Mon, 18 May 2020 19:41:38 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.3.0-dev0-464-g810d66a-fmstable-20200518v1 Mime-Version: 1.0 Message-Id: In-Reply-To: References: <000000000000b4684e05a2968ca6@google.com> Date: Mon, 18 May 2020 19:41:18 -0400 From: "Colin Walters" To: "Miklos Szeredi" , "Mike Kravetz" Cc: syzbot , "Andrew Morton" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Miklos Szeredi" , syzkaller-bugs , "Al Viro" Subject: Re: kernel BUG at mm/hugetlb.c:LINE! Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 12, 2020, at 11:04 AM, Miklos Szeredi wrote: > > However, in this syzbot test case the 'file' is in an overlayfs filesystem > > created as follows: > > > > mkdir("./file0", 000) = 0 > > mount(NULL, "./file0", "hugetlbfs", MS_MANDLOCK|MS_POSIXACL, NULL) = 0 > > chdir("./file0") = 0 > > mkdir("./file1", 000) = 0 > > mkdir("./bus", 000) = 0 > > mkdir("./file0", 000) = 0 > > mount("\177ELF\2\1\1", "./bus", "overlay", 0, "lowerdir=./bus,workdir=./file1,u"...) = 0 Is there any actual valid use case for mounting an overlayfs on top of hugetlbfs? I can't think of one. Why isn't the response to this to instead only allow mounting overlayfs on top of basically a set of whitelisted filesystems?