From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965076Ab3DJJgK (ORCPT ); Wed, 10 Apr 2013 05:36:10 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:32884 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759913Ab3DJJgH (ORCPT ); Wed, 10 Apr 2013 05:36:07 -0400 Date: Wed, 10 Apr 2013 10:35:55 +0100 From: Luis Henriques To: Ben Hutchings Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com, Matthew Garrett , Josh Boyer , Michael Schroeder , "Lee, Chun-Yi" , Lingzhu Xiang , Seiji Aguchi , Matt Fleming Subject: Re: [PATCH 097/102] efivars: explicitly calculate length of VariableName Message-ID: <20130410093555.GA3049@hercules> References: <1365414657-29191-1-git-send-email-luis.henriques@canonical.com> <1365414657-29191-98-git-send-email-luis.henriques@canonical.com> <1365547506.5814.36.camel@deadeye.wl.decadent.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1365547506.5814.36.camel@deadeye.wl.decadent.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 09, 2013 at 11:45:06PM +0100, Ben Hutchings wrote: > On Mon, 2013-04-08 at 10:50 +0100, Luis Henriques wrote: > > 3.5.7.10 -stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Matt Fleming > > > > commit ec50bd32f1672d38ddce10fb1841cbfda89cfe9a upstream. > > > > It's not wise to assume VariableNameSize represents the length of > > VariableName, as not all firmware updates VariableNameSize in the same > > way (some don't update it at all if EFI_SUCCESS is returned). There > > are even implementations out there that update VariableNameSize with > > values that are both larger than the string returned in VariableName > > and smaller than the buffer passed to GetNextVariableName(), which > > resulted in the following bug report from Michael Schroeder, > > > > > On HP z220 system (firmware version 1.54), some EFI variables are > > > incorrectly named : > > > > > > ls -d /sys/firmware/efi/vars/*8be4d* | grep -v -- -8be returns > > > /sys/firmware/efi/vars/dbxDefault-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > > /sys/firmware/efi/vars/KEKDefault-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > > /sys/firmware/efi/vars/SecureBoot-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > > /sys/firmware/efi/vars/SetupMode-Information8be4df61-93ca-11d2-aa0d-00e098032b8c > > > > The issue here is that because we blindly use VariableNameSize without > > verifying its value, we can potentially read garbage values from the > > buffer containing VariableName if VariableNameSize is larger than the > > length of VariableName. > > > > Since VariableName is a string, we can calculate its size by searching > > for the terminating NULL character. > > > > Reported-by: Frederic Crozat > > Cc: Matthew Garrett > > Cc: Josh Boyer > > Cc: Michael Schroeder > > Cc: Lee, Chun-Yi > > Cc: Lingzhu Xiang > > Cc: Seiji Aguchi > > Signed-off-by: Matt Fleming > > [ Backported for 3.4-stable. Removed workqueue code added in a93bc0c 3.9-rc1. ] > [...] > > I thought the workqueue addition was a worthwhile fix in its own right, > so for 3.2.y I cherry-picked that as well. Ok, makes sense to me too. So here's what I'll do: for this release I'll just drop this commit and e971318bbed610e28bb3fde9d548e6aaf0a6b02e ('efivars: Handle duplicate names from get_next_variable()'). I'll queue them again for next release along with commit a93bc0c6e07ed9bac44700280e65e2945d864fd4 ('efi_pstore: Introducing workqueue updating sysfs'). Thanks for your review Ben. Cheers, -- Luis