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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 90B76C4346E for ; Tue, 29 Sep 2020 06:38:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 516EA2083B for ; Tue, 29 Sep 2020 06:38:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725776AbgI2GiR (ORCPT ); Tue, 29 Sep 2020 02:38:17 -0400 Received: from verein.lst.de ([213.95.11.211]:38344 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725372AbgI2GiR (ORCPT ); Tue, 29 Sep 2020 02:38:17 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 47E336736F; Tue, 29 Sep 2020 08:38:15 +0200 (CEST) Date: Tue, 29 Sep 2020 08:38:15 +0200 From: Christoph Hellwig To: Eric Biggers Cc: Christoph Hellwig , David Laight , syzbot+51177e4144d764827c45@syzkaller.appspotmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Subject: Re: WARNING in __kernel_read (2) Message-ID: <20200929063815.GB1839@lst.de> References: <000000000000da992305b02e9a51@google.com> <3b3de066852d4e30bd9d85bd28023100@AcuMS.aculab.com> <642ed0b4810d44ab97a7832ccb8b3e44@AcuMS.aculab.com> <20200928221441.GF1340@sol.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200928221441.GF1340@sol.localdomain> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Sep 28, 2020 at 03:14:41PM -0700, Eric Biggers wrote: > On Sat, Sep 26, 2020 at 01:17:04PM +0000, David Laight wrote: > > From: David Laight > > > Sent: 26 September 2020 12:16 > > > To: 'syzbot' ; linux-fsdevel@vger.kernel.org; > > > linux-kernel@vger.kernel.org; syzkaller-bugs@googlegroups.com; viro@zeniv.linux.org.uk > > > Subject: RE: WARNING in __kernel_read (2) > > > > > > > From: syzbot > > > > Sent: 26 September 2020 03:58 > > > > To: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; syzkaller-bugs@googlegroups.com; > > > > viro@zeniv.linux.org.uk > > > > Subject: WARNING in __kernel_read (2) > > > > > > I suspect this is calling finit_module() on an fd > > > that doesn't have read permissions. > > > > Code inspection also seems to imply that the check means > > the exec() also requires read permissions on the file. > > > > This isn't traditionally true. > > suid #! scripts are particularly odd without 'owner read' > > (everyone except the owner can run them!). > > Christoph, any thoughts here? You added this WARN_ON_ONCE in: > > commit 61a707c543e2afe3aa7e88f87267c5dafa4b5afa > Author: Christoph Hellwig > Date: Fri May 8 08:54:16 2020 +0200 > > fs: add a __kernel_read helper Linus asked for it. What is the call chain that we hit it with?