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

[Lingzhu Xiang <lxiang@redhat.com>]

On 03/01/2013 11:20 AM, Lee, Chun-Yi wrote:
> From: Michael Schroeder <mls@suse.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