Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935844Ab3DPKdh (ORCPT ); Tue, 16 Apr 2013 06:33:37 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:51222 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752892Ab3DPKdf (ORCPT ); Tue, 16 Apr 2013 06:33:35 -0400 Date: Tue, 16 Apr 2013 11:33:21 +0100 From: Luis Henriques To: Seiji Aguchi Cc: Matt Fleming , Lingzhu Xiang , Josh Boyer , "linux-kernel@vger.kernel.org" , stable@vger.kernel.org, "Lee, Chun-Yi" , "kernel-team@lists.ubuntu.com" , Michael Schroeder , Ben Hutchings Subject: Re: [PATCH 097/102] efivars: explicitly calculate length of VariableName Message-ID: <20130416103321.GB3054@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> <51653E81.4090102@redhat.com> <20130410121730.GB3049@hercules> <20130411091256.GA11370@hercules> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130411091256.GA11370@hercules> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6403 Lines: 123 (Adding Ben back to the CC list; not sure how his email was dropped) On Thu, Apr 11, 2013 at 10:12:56AM +0100, Luis Henriques wrote: > On Wed, Apr 10, 2013 at 03:57:12PM +0000, Seiji Aguchi wrote: > > > > > > > -----Original Message----- > > > From: Luis Henriques [mailto:luis.henriques@canonical.com] > > > Sent: Wednesday, April 10, 2013 8:18 AM > > > To: Lingzhu Xiang > > > Cc: Ben Hutchings; Seiji Aguchi; linux-kernel@vger.kernel.org; stable@vger.kernel.org; kernel-team@lists.ubuntu.com; Matthew > > > Garrett; Josh Boyer; Michael Schroeder; Lee, Chun-Yi; Matt Fleming > > > Subject: Re: [PATCH 097/102] efivars: explicitly calculate length of VariableName > > > > > > On Wed, Apr 10, 2013 at 06:27:13PM +0800, Lingzhu Xiang wrote: > > > > On 04/10/2013 06:45 AM, 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. > > > > > > > > FWIW, the workqueue patch is 1/2 of this patchset[1] fixing closely > > > > related problems. The other one is 81fa4e58. > > > > > > > > [1]: http://article.gmane.org/gmane.linux.kernel/1439570 > > > > > > > > I tried to avoid pulling too much for stable because the patchset is > > > > quite large and I suspect the problem it fixes is only theoretical. > > > > I reported the original bug but was unable to break anything except > > > > getting call traces with various CONFIG_DEBUG_*. > > > > > > > > What's your opinion, Seiji? > > > > > > Ok, so just to clarify: you're suggesting me to pick the following commits: > > > > > > 81fa4e581d9283f7992a0d8c534bb141eb840a14 efivars: Disable external interrupt while holding efivars->lock > > > a93bc0c6e07ed9bac44700280e65e2945d864fd4 efi_pstore: Introducing workqueue updating sysfs > > > ec50bd32f1672d38ddce10fb1841cbfda89cfe9a efivars: explicitly calculate length of VariableName > > > e971318bbed610e28bb3fde9d548e6aaf0a6b02e efivars: Handle duplicate names from get_next_variable() > > > > I agree to add these commits to a stable tree. > > > Thank you Seiji. I'll queue these for the next 3.5 kernel. So, after spending some time around this, I ended up picking much more commits than those listed above. Since this code in 3.5.y wasn't that different from Ben's 3.2.y, I took the liberty of picking all the bits I was missing from there. Here's what I ended up with: d80a361d779a9f19498943d1ca84243209cd5647 efi_pstore: Check remaining space with QueryVariableInfo() before writing data 81fa4e581d9283f7992a0d8c534bb141eb840a14 efivars: Disable external interrupt while holding efivars->lock 68d929862e29a8b52a7f2f2f86a0600423b093cd efi: be more paranoid about available space when creating variables ed9dc8ce7a1c8115dba9483a9b51df8b63a2e0ef efivars: Allow disabling use as a pstore backend ec0971ba5372a4dfa753f232449d23a8fd98490e efivars: Add module parameter to disable use as a pstore backend ca0ba26fbbd2d81c43085df49ce0abfe34535a90 efivars: Fix check for CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE a93bc0c6e07ed9bac44700280e65e2945d864fd4 efi_pstore: Introducing workqueue updating sysfs ec50bd32f1672d38ddce10fb1841cbfda89cfe9a efivars: explicitly calculate length of VariableName e971318bbed610e28bb3fde9d548e6aaf0a6b02e efivars: Handle duplicate names from get_next_variable() efivars: pstore: Do not check size when erasing variable (this last commit was picked from 3.2.y directly, its not an upstream commit) I'll be sending out 3.5.7.11 for review later this week, and I would really appreciate any feedback on these commits. (Ben: Thanks a lot, since most of the backport work was took from your tree.) Cheers, -- Luis -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/