Re: [PATCH] efi: mokvar-table: fix some issues in new code

[Lenny Szubowicz <lszubowi@redhat.com>]

On 9/24/20 3:12 PM, Arvind Sankar wrote:
> On Thu, Sep 24, 2020 at 06:05:46PM +0200, Ard Biesheuvel wrote:
>> Fix a couple of issues in the new mokvar-table handling code, as
>> pointed out by Arvind and Boris:
>> - don't bother checking the end of the physical region against the start
>>    address of the mokvar table,
>> - ensure that we enter the loop with err = -EINVAL,
>> - replace size_t with unsigned long to appease pedantic type equality
>>    checks.
>>
>> Cc: Lenny Szubowicz <lszubowi@redhat.com>
>> Cc: Borislav Petkov <bp@alien8.de>
>> Cc: Arvind Sankar <nivedita@alum.mit.edu>
>> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> 
> Reviewed-by: Arvind Sankar <nivedita@alum.mit.edu>

Reviewed-by: Lenny Szubowicz <lszubowi@redhat.com>

> 
>> ---
>>   drivers/firmware/efi/mokvar-table.c | 25 +++++++++++--------------
>>   1 file changed, 11 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/firmware/efi/mokvar-table.c b/drivers/firmware/efi/mokvar-table.c
>> index b1cd49893d4d..72a9e1736fef 100644
>> --- a/drivers/firmware/efi/mokvar-table.c
>> +++ b/drivers/firmware/efi/mokvar-table.c
>> @@ -98,15 +98,14 @@ static struct kobject *mokvar_kobj;
>>   void __init efi_mokvar_table_init(void)
>>   {
>>   	efi_memory_desc_t md;
>> -	u64 end_pa;
>>   	void *va = NULL;
>> -	size_t cur_offset = 0;
>> -	size_t offset_limit;
>> -	size_t map_size = 0;
>> -	size_t map_size_needed = 0;
>> -	size_t size;
>> +	unsigned long cur_offset = 0;
>> +	unsigned long offset_limit;
>> +	unsigned long map_size = 0;
>> +	unsigned long map_size_needed = 0;
>> +	unsigned long size;
>>   	struct efi_mokvar_table_entry *mokvar_entry;
>> -	int err = -EINVAL;
>> +	int err;
>>   
>>   	if (!efi_enabled(EFI_MEMMAP))
>>   		return;
>> @@ -122,18 +121,16 @@ void __init efi_mokvar_table_init(void)
>>   		pr_warn("EFI MOKvar config table is not within the EFI memory map\n");
>>   		return;
>>   	}
>> -	end_pa = efi_mem_desc_end(&md);
>> -	if (efi.mokvar_table >= end_pa) {
>> -		pr_err("EFI memory descriptor containing MOKvar config table is invalid\n");
>> -		return;
>> -	}
>> -	offset_limit = end_pa - efi.mokvar_table;
>> +
>> +	offset_limit = efi_mem_desc_end(&md) - efi.mokvar_table;
>> +
>>   	/*
>>   	 * Validate the MOK config table. Since there is no table header
>>   	 * from which we could get the total size of the MOK config table,
>>   	 * we compute the total size as we validate each variably sized
>>   	 * entry, remapping as necessary.
>>   	 */
>> +	err = -EINVAL;
>>   	while (cur_offset + sizeof(*mokvar_entry) <= offset_limit) {
>>   		mokvar_entry = va + cur_offset;
>>   		map_size_needed = cur_offset + sizeof(*mokvar_entry);
>> @@ -150,7 +147,7 @@ void __init efi_mokvar_table_init(void)
>>   				       offset_limit);
>>   			va = early_memremap(efi.mokvar_table, map_size);
>>   			if (!va) {
>> -				pr_err("Failed to map EFI MOKvar config table pa=0x%lx, size=%zu.\n",
>> +				pr_err("Failed to map EFI MOKvar config table pa=0x%lx, size=%lu.\n",
>>   				       efi.mokvar_table, map_size);
>>   				return;
>>   			}
>> -- 
>> 2.17.1
>>
>