Re: [PATCH V2] xen: Check if the range is valid in init_domheap_pages

[Julien Grall <julien.grall@linaro.org>]

On 11/13/2013 01:23 PM, Ian Campbell wrote:
> On Wed, 2013-11-13 at 13:15 +0000, Julien Grall wrote:
>> On ARM, when an initrd is given to xen by U-boot, it will reserve the memory in
>> the device tree.
>> In this case, when xen decides to free unused memory, dt_unreserved_regions
>> will call init_domheap_pages with the start and the end of range equals. But
>> the latter assumes that (start > end), if not Xen will hang because the
>> number of pages is equals to (unsigned)-1.
>>
>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>> CC: Keir Fraser <keir@xen.org>
>> CC: Jan Beulich <jbeulich@suse.com>
>>
>> ---
>>      Changes in v2:
>>          - Change commit title
>>          - Move the check in init_domheap_pages
>> ---
>>   xen/common/page_alloc.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
>> index 4c17fbd..10f67a1 100644
>> --- a/xen/common/page_alloc.c
>> +++ b/xen/common/page_alloc.c
>> @@ -1429,6 +1429,9 @@ void init_domheap_pages(paddr_t ps, paddr_t pe)
>>       smfn = round_pgup(ps) >> PAGE_SHIFT;
>>       emfn = round_pgdown(pe) >> PAGE_SHIFT;
>>
>> +    if ( smfn <= emfn )
>
> You've got this backwards I think.

Oh right, I will fix it in the next version.

>
>> +        return;
>> +
>>       init_heap_pages(mfn_to_page(smfn), emfn - smfn);
>>   }
>>
>
>

-- 
Julien Grall