[PATCH] powerpc/book3s64: Fix error handling in mm_iommu_do_alloc()

Alexey Kardashevskiy aik at ozlabs.ru
Mon Dec 23 11:57:17 AEDT 2019



On 20/12/2019 20:57, Jan Kara wrote:
> On Fri 20-12-19 16:06:05, Alexey Kardashevskiy wrote:
>>
>>
>> On 11/12/2019 21:42, Jan Kara wrote:
>>> The last jump to free_exit in mm_iommu_do_alloc() happens after page
>>> pointers in struct mm_iommu_table_group_mem_t were already converted to
>>> physical addresses. Thus calling put_page() on these physical addresses
>>> will likely crash. Convert physical addresses back to page pointers
>>> during the error cleanup.
>>>
>>> Signed-off-by: Jan Kara <jack at suse.cz>
>>> ---
>>>  arch/powerpc/mm/book3s64/iommu_api.c | 5 ++++-
>>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>>  Beware, this is completely untested, spotted just by code audit.
>>>
>>> diff --git a/arch/powerpc/mm/book3s64/iommu_api.c b/arch/powerpc/mm/book3s64/iommu_api.c
>>> index 56cc84520577..06c403381c9c 100644
>>> --- a/arch/powerpc/mm/book3s64/iommu_api.c
>>> +++ b/arch/powerpc/mm/book3s64/iommu_api.c
>>> @@ -154,7 +154,7 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
>>>  				       (mem2->entries << PAGE_SHIFT)))) {
>>>  			ret = -EINVAL;
>>>  			mutex_unlock(&mem_list_mutex);
>>> -			goto free_exit;
>>> +			goto convert_exit;
>>>  		}
>>>  	}
>>>  
>>> @@ -166,6 +166,9 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
>>>  
>>>  	return 0;
>>>  
>>> +convert_exit:
>>> +	for (i = 0; i < pinned; i++)
>>> +		mem->hpages[i] = pfn_to_page(mem->hpas[i] >> PAGE_SHIFT);
>>
>>
>> Good find. Although doing it where you added "goto convert_exit" seems
>> cleaner imho. Thanks,
> 
> I don't really care :). V2 attached.


Usually patches are posted using git send-mail, not as attachment. A
nit: v2 has now curly braces which v1 did not.

Either way, v2 is correct.


Tested-by: Alexey Kardashevskiy <aik at ozlabs.ru>
Reviewed-by: Alexey Kardashevskiy <aik at ozlabs.ru>





-- 
Alexey


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