linux-kernel - Re: [PATCH] efivarfs: fix abnormal GUID in variable name by using strcpy to replace null with dash

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Date:	Wed, 06 Mar 2013 15:39:49 +0800
From:	joeyli <jlee@...e.com>
To:	Matt Fleming <matt@...sole-pimps.org>
Cc:	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Michael Schroeder <mls@...e.com>,
	Josh Boyer <jwboyer@...hat.com>,
	Peter Jones <pjones@...hat.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Frederic Crozat <fcrozat@...e.com>
Subject: Re: [PATCH] efivarfs: fix abnormal GUID in variable name by using
 strcpy to replace null with dash

於 三，2013-03-06 於 15:34 +0800，joeyli 提到：
> Hi Matt, 
> 
> 於 六，2013-03-02 於 07:41 +0800，joeyli 提到：
> > 於 五，2013-03-01 於 16:31 +0000，Matt Fleming 提到：
> > > On Fri, 2013-03-01 at 15:17 +0000, Matt Fleming wrote:
> > > > On Fri, 2013-03-01 at 11:20 +0800, Lee, Chun-Yi wrote:
> > > > > From: Michael Schroeder <mls@...e.com>
> > > > > 
> > > > > 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
> > > > > 
> > > > > That causes by the following statement in
> efivar_create_sysfs_entry function:
> > > > > 
> > > > >  *(short_name + strlen(short_name)) = '-';
> > > > > efi_guid_unparse(vendor_guid, short_name +
> strlen(short_name));
> > > > > 
> > > > > The trailing \0 is overwritten with '-', but the next char
> doesn't seem to be a \0
> > > > > as well for HP. So, the second strlen return the point of next
> '\0', causes there
> > > > > have garbage string attached before GUID.
> > > > > 
> > > > > Tested on On HP z220.
> > > > 
> > > > What's more likely happening here is that GetNextVariable() is
> broken on
> > > > this HP firmware and variable_name_size is too big for the given
> > > > variable in variable_name. We've seen other reports of similar
> bugs,
> > > > 
> > > >   https://bugzilla.kernel.org/show_bug.cgi?id=47631
> > > > 
> > > > 
> > > > Could someone try this patch against Linus' tree?
> > > 
> > > Urgh, and here's a version that isn't utterly, utterly broken...
> > 
> > Thanks for Matt's patch, we will try it!
> > 
> > Joey Lee
> 
> Frederic confirmed your patch works to him for fix issue on HP
> machine.
> 
> Tested-by: Frederic Crozat <fcrozat@...e.com>

Sorry forgot paste variable_name_size from log:

efivars: bogus variable_name_size: 34 1024
efivars: bogus variable_name_size: 22 1024

The GetNextVariable() always return variable_name_size is 1024.


Thanks a lot!
Joey Lee

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