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

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Date:	Fri, 01 Mar 2013 22:49:35 +0800
From:	joeyli <jlee@...e.com>
To:	Lingzhu Xiang <lxiang@...hat.com>
Cc:	matt@...sole-pimps.org, linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Michael Schroeder <mls@...e.com>,
	Josh Boyer <jwboyer@...hat.com>,
	Jeremy Kerr <jeremy.kerr@...onical.com>
Subject: Re: [PATCH] efivarfs: fix abnormal GUID in variable name by using
 strcpy to replace null with dash

於 五，2013-03-01 於 17:31 +0800，Lingzhu Xiang 提到：
> On 03/01/2013 11:20 AM, 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.
> 
> So short_name has trailing garbage, or rather, variable_name_size
> is larger than variable_name actually is, wouldn't new_efivar->var.VariableName
> also gets filled with trailing garbage?
> 
> In efivar_store_raw the VariableName's trailing garbage can cause
> problem for comparison. You might want to also cover that or fix
> variable_name_size.
> 
> 
> Lingzhu Xiang
> 

Yes, it's possible! I will add patch for print more debug messages to
bug reporter for check it.


Thanks for your review!
Joey Lee


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