[PATCH 1/1] spl: spl_legacy: simplify spl_parse_legacy_validate

[Heinrich Schuchardt]

On 7/22/23 21:09, Marek Vasut wrote:
> On 7/22/23 20:46, Heinrich Schuchardt wrote:
>> The check for an overlap of the loaded image and SPL is overly
>> complicated.
>>
>> Fixes: 77aed22b48ab ("spl: spl_legacy: Add extra address checks")
>> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
>> ---
>>   common/spl/spl_legacy.c | 5 +----
>>   1 file changed, 1 insertion(+), 4 deletions(-)
>>
>> diff --git a/common/spl/spl_legacy.c b/common/spl/spl_legacy.c
>> index 095443c63d..9246f555e3 100644
>> --- a/common/spl/spl_legacy.c
>> +++ b/common/spl/spl_legacy.c
>> @@ -22,10 +22,7 @@ static void spl_parse_legacy_validate(uintptr_t 
>> start, uintptr_t size)
>>       uintptr_t spl_end = (uintptr_t)_image_binary_end;
>>       uintptr_t end = start + size;
>> -    if ((start >= spl_start && start < spl_end) ||
>> -        (end > spl_start && end <= spl_end) ||
>> -        (start < spl_start && end >= spl_end) ||
>> -        (start > end && end > spl_start))
>> +    if (end > spl_start && start < spl_end)
>>           panic("SPL: Image overlaps SPL\n");
>>       if (size > CONFIG_SYS_BOOTM_LEN)
> 
> Does this handle address space wrap around ? This:
> 
> =====blob=====|..............|=====blob=====
> .....|==spl==|..............................
> 
> Hint: it does not.

The replaced code does not handle wrap around where end is below 
spl_start. The following code would cover all cases of image wrap around:

+	if (end > spl_start && start < spl_end
+		panic("SPL: Image overlaps SPL\n");
+	if (start >= end)
+		panic("SPL: Image wraps around\n");

I guess we don't have to test for spl_start >= spl_end.

> 
> +CC Rasmus.
> 
> Look at all the other checks in U-Boot which do, and first factor them 

Which other instances do you refer to?

The lmb library does not to check for wrap around but the wrap around 
checks would have to be in other places than lmb_addrs_overlap().

Best regards

Heinrich

> out into one check functions, so we can improve on that one. Second, use 
> that function all over the place. Third, improve on it.