PATCH: bug in locate_hole()

[Matthew Fleming]

On Mon, Mar 3, 2014 at 8:03 PM, Simon Horman <horms at verge.net.au> wrote:
> Thanks Matthew.
>
> Could you provide a signed-off-by line?

I'm not sure what that would look like.  Do I sign off on my own patch?

Thanks,
matthew


> On Mon, Mar 03, 2014 at 04:34:35PM -0800, Matthew Fleming wrote:
>> In upgrading to kexec-tools 2.0.5 I first got the error "Overlapping
>> memory segments at 0xbeff000"
>>
>> Adding some debugging I found locate_hole was returning incorrect
>> values.  The below is from the debug I added:
>>
>> XXXMDF: look for hole size 100000, cur range [52b3000, bffffff] size 6d4cfff
>> XXXMDF: look for hole memsz=100000, found beff000
>>
>> Hmm, if we wanted 0x100000 bytes ending at 0xbffffff, that should be
>> 0xbf00000, not 0xbef000.  Continuing to the second invocation:
>>
>> XXXMDF: look for hole size 1000, cur range [52b3000, befefff] size 6c4bfff
>> XXXMDF: look for hole size 1000, cur range [bfff000, bffffff] size fff
>> XXXMDF: look for hole memsz=1000, found bffe000
>>
>> Now we die with overlapping ranges, since the 0x100000 bytes at
>> 0xbeff000 overlaps 0x1000 bytes at 0xbffe000.
>>
>> The attached patch fixes the off-by-one that causes the later overlap.
>>
>> Thanks,
>> matthew
>
>> --- kexec.c.orig      2014-03-03 16:08:53.289844106 -0800
>> +++ kexec.c   2014-03-03 16:09:04.960844107 -0800
>> @@ -272,17 +272,17 @@ unsigned long locate_hole(struct kexec_i
>>               }
>>               /* Is there enough space left so we can use it? */
>>               size = end - start;
>>               if (!hole_size || size >= hole_size - 1) {
>>                       if (hole_end > 0) {
>>                               hole_base = start;
>>                               break;
>>                       } else {
>> -                             hole_base = _ALIGN_DOWN(end - hole_size,
>> +                             hole_base = _ALIGN_DOWN(end - hole_size + 1,
>>                                       hole_align);
>>                       }
>>               }
>>       }
>>       free(mem_range);
>>       if (hole_base == ULONG_MAX) {
>>               fprintf(stderr, "Could not find a free area of memory of "
>>                       "0x%lx bytes...\n", hole_size);
>
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>