[U-Boot] [PATCH 07/15] efi_loader: remove limit on variable length

[Heinrich Schuchardt]

On 08/26/2018 08:13 PM, Alexander Graf wrote:
> 
> 
> On 11.08.18 17:28, Heinrich Schuchardt wrote:
>> The EFI spec does not provide a length limit for variables.
>>
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>> ---
>>  lib/efi_loader/efi_variable.c | 52 ++++++++++++++++++++---------------
>>  1 file changed, 30 insertions(+), 22 deletions(-)
>>
>> diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
>> index 770c67abb9..495738884b 100644
>> --- a/lib/efi_loader/efi_variable.c
>> +++ b/lib/efi_loader/efi_variable.c
>> @@ -44,10 +44,7 @@
>>   * converted to utf16?
>>   */
>>  
>> -#define MAX_VAR_NAME 31
>> -#define MAX_NATIVE_VAR_NAME \
>> -	(strlen("efi_xxxxxxxx-xxxx-xxxx-xxxxxxxxxxxxxxxx_") + \
>> -		(MAX_VAR_NAME * MAX_UTF8_PER_UTF16))
>> +#define PREFIX_LEN (strlen("efi_xxxxxxxx-xxxx-xxxx-xxxxxxxxxxxxxxxx_"))
>>  
>>  static int hex(int ch)
>>  {
>> @@ -101,18 +98,20 @@ static char *mem2hex(char *hexstr, const u8 *mem, int count)
>>  	return hexstr;
>>  }
>>  
>> -static efi_status_t efi_to_native(char *native, u16 *variable_name,
>> +static efi_status_t efi_to_native(char **native, const u16 *variable_name,
>>  				  efi_guid_t *vendor)
>>  {
>>  	size_t len;
>> +	char *pos;
>>  
>> -	len = u16_strlen((u16 *)variable_name);
>> -	if (len >= MAX_VAR_NAME)
>> -		return EFI_DEVICE_ERROR;
>> +	len = PREFIX_LEN + utf16_utf8_strlen(variable_name) + 1;
>> +	*native = malloc(len);
>> +	if (!*native)
>> +		return EFI_OUT_OF_RESOURCES;
>>  
>> -	native += sprintf(native, "efi_%pUl_", vendor);
>> -	native  = (char *)utf16_to_utf8((u8 *)native, (u16 *)variable_name, len);
>> -	*native = '\0';
>> +	pos = *native;
>> +	pos += sprintf(pos, "efi_%pUl_", vendor);
>> +	utf16_utf8_strcpy(&pos, variable_name);
>>  
>>  	return EFI_SUCCESS;
>>  }
>> @@ -168,7 +167,7 @@ efi_status_t EFIAPI efi_get_variable(u16 *variable_name, efi_guid_t *vendor,
>>  				     u32 *attributes, efi_uintn_t *data_size,
>>  				     void *data)
>>  {
>> -	char native_name[MAX_NATIVE_VAR_NAME + 1];
>> +	char *native_name;
> 
> I think you want to predefine this to = NULL to make sure that an error
> path doesn't give you uninitialized values on free().

efi_to_native() returns EFI_OUT_OF_RESOURCES if the pointer cannot be
assigned and the return value is checked. So how should I reach
free(native_name) in this case?

Best regards

Heinrich

> 
> 
> Alex
>