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=-8.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 613C2C3A5A9 for ; Wed, 4 Sep 2019 07:19:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2C96A2339E for ; Wed, 4 Sep 2019 07:19:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567581574; bh=agWnI6rJaNdK4UMwnHBLhmqSgnDlx6mMyBHN9X1yZg0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=0EDiL18C27Wo7wZfJisV7OMqhJFz2kTdaA1ACj40y+eE2nX2KkVp6vpXfKJ3hdPNN pAtqqJ0VXo4Z/ATtk8oA5LFneV//8ByI5aUD+d9Tpi0s4eZKYfkEWjmynDPSgQMyMk U9uBi4+eKa+fx2bG52iRJjoZW4RqhOLKzJZ9VyDE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729017AbfIDHTd (ORCPT ); Wed, 4 Sep 2019 03:19:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:36042 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726033AbfIDHTd (ORCPT ); Wed, 4 Sep 2019 03:19:33 -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 634872339D; Wed, 4 Sep 2019 07:19:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567581571; bh=agWnI6rJaNdK4UMwnHBLhmqSgnDlx6mMyBHN9X1yZg0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=w9wfwQhZZgfWDk5hLe7xZr/Nozm/Tm6ZFe7ClleLnfdOCIAXfsvTuJ4a7SlzOGqGD YN+HZIrs+6145OnTEBQ8AipFGiZwEWRDXPxCySmjhyxobbjV8tXSDaiNHeZWUZF4B0 4khMHThIJpaBxaYCCjWpdX9f+wH3UPw3vrfmFY3E= Date: Wed, 4 Sep 2019 09:19:29 +0200 From: Greg Kroah-Hartman To: Hridya Valsaraju Cc: Christian Brauner , devel@driverdev.osuosl.org, kernel-team@android.com, Todd Kjos , linux-kernel@vger.kernel.org, Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Joel Fernandes , Martijn Coenen Subject: Re: [PATCH v3 2/2] binder: Validate the default binderfs device names. Message-ID: <20190904071929.GA19830@kroah.com> References: <20190808222727.132744-1-hridya@google.com> <20190808222727.132744-3-hridya@google.com> <20190809145508.GD16262@kroah.com> <20190809181439.qrs2k7l23ot4am4s@wittgenstein> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 09, 2019 at 11:41:12AM -0700, Hridya Valsaraju wrote: > On Fri, Aug 9, 2019 at 11:14 AM Christian Brauner > wrote: > > > > On Fri, Aug 09, 2019 at 04:55:08PM +0200, Greg Kroah-Hartman wrote: > > > On Thu, Aug 08, 2019 at 03:27:26PM -0700, Hridya Valsaraju wrote: > > > > Length of a binderfs device name cannot exceed BINDERFS_MAX_NAME. > > > > This patch adds a check in binderfs_init() to ensure the same > > > > for the default binder devices that will be created in every > > > > binderfs instance. > > > > > > > > Co-developed-by: Christian Brauner > > > > Signed-off-by: Christian Brauner > > > > Signed-off-by: Hridya Valsaraju > > > > --- > > > > drivers/android/binderfs.c | 12 ++++++++++++ > > > > 1 file changed, 12 insertions(+) > > > > > > > > diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c > > > > index aee46dd1be91..55c5adb87585 100644 > > > > --- a/drivers/android/binderfs.c > > > > +++ b/drivers/android/binderfs.c > > > > @@ -570,6 +570,18 @@ static struct file_system_type binder_fs_type = { > > > > int __init init_binderfs(void) > > > > { > > > > int ret; > > > > + const char *name; > > > > + size_t len; > > > > + > > > > + /* Verify that the default binderfs device names are valid. */ > > > > > > And by "valid" you only mean "not bigger than BINDERFS_MAX_NAME, right? > > > > > > > + name = binder_devices_param; > > > > + for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { > > > > + if (len > BINDERFS_MAX_NAME) > > > > + return -E2BIG; > > > > + name += len; > > > > + if (*name == ',') > > > > + name++; > > > > + } > > > > > > We already tokenize the binderfs device names in binder_init(), why not > > > check this there instead? Parsing the same string over and over isn't > > > the nicest. > > > > non-binderfs binder devices do not have their limit set to > > BINDERFS_NAME_MAX. That's why the check has likely been made specific to > > binderfs binder devices which do have that limit. > > > Thank you Greg and Christian, for taking another look. Yes, > non-binderfs binder devices not having this limitation is the reason > why the check was made specific to binderfs devices. Also, when > CONFIG_ANDROID_BINDERFS is set, patch 1/2 disabled the same string > being parsed in binder_init(). > > > > > But, in practice, 255 is the standard path-part limit that no-one really > > exceeds especially not for stuff such as device nodes which usually have > > rather standard naming schemes (e.g. binder, vndbinder, hwbinder, etc.). > > So yes, we can move that check before both the binderfs binder device > > and non-binderfs binder device parsing code and treat it as a generic > > check. > > Then we can also backport that check as you requested in the other mail. > > Unless Hridya or Todd have objections, of course. > > I do not have any objections to adding a generic check in binder_init() instead. Was this patchset going to be redone based on this? thanks, greg k-h