Re: [PATCH 2/2] kasan: Fix a type conversion error

[long.wanglong]

On 2015/9/9 17:01, Vladimir Murzin wrote:
> On 09/09/15 04:59, Wang Long wrote:
>> The current KASAN code can find the following out-of-bounds
> 
> Should it be "cannot"?
> 
> Vladimir
> 
sorry for that mistake, it should be "cannot".

>> bugs:
>> 	char *ptr;
>> 	ptr = kmalloc(8, GFP_KERNEL);
>> 	memset(ptr+7, 0, 2);
>>
>> the cause of the problem is the type conversion error in
>> *memory_is_poisoned_n* function. So this patch fix that.
>>
>> Signed-off-by: Wang Long <long.wanglong@xxxxxxxxxx>
>> ---
>>  mm/kasan/kasan.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
>> index 7b28e9c..5d65d06 100644
>> --- a/mm/kasan/kasan.c
>> +++ b/mm/kasan/kasan.c
>> @@ -204,7 +204,7 @@ static __always_inline bool memory_is_poisoned_n(unsigned long addr,
>>  		s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
>>  
>>  		if (unlikely(ret != (unsigned long)last_shadow ||
>> -			((last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
>> +			((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
>>  			return true;
>>  	}
>>  	return false;
>>
> 
> 
> .
> 


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