Re: [Qemu-devel] [PATCH] exec: Fix section_covers_addr() for sections with non-zero offset

[BALATON Zoltan <balaton@eik.bme.hu>]

On Tue, 14 Nov 2017, Paolo Bonzini wrote:
> On 21/10/2017 13:24, BALATON Zoltan wrote:
>> diff --git a/exec.c b/exec.c
>> index db5ae23..a915817 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -370,7 +370,8 @@ static inline bool section_covers_addr(const MemoryRegionSection *section,
>>       * the section must cover the entire address space.
>>       */
>>      return int128_gethi(section->size) ||
>> -           range_covers_byte(section->offset_within_address_space,
>> +           range_covers_byte(section->offset_within_address_space +
>> +                             section->offset_within_region,
>>                               int128_getlo(section->size), addr);
>>  }
>
> Sorry, this is incorrect.  addr is an address in the address space, and
> range_covers_byte checks if it is between
> section->offset_within_address_space and
> section->offset_within_address_space + section->size.  I am not sure how
> things don't explode completely by adding section->offset_within_region
> (probably it's just because section->offset_within_region is usually 0).

I had a feeling this might not be correct but appeared to work, very 
likely because in most cases the offset is 0 (which is why the bug wasn't 
happening very often either). How about the alternative I've just sent 
according to your suggestion? That also appears to fix the problem and 
hopefully more correct.

Thank you,
BALATON Zoltan