Re: [PATCH v1 3/3] KVM: s390: generalize kvm_s390_get_tod_clock_ext()

[Janosch Frank <frankja@xxxxxxxxxxxxx>]

On 02.05.2018 21:40, David Hildenbrand wrote:
> On 02.05.2018 21:36, Christian Borntraeger wrote:
>>
>>
>> On 04/27/2018 02:36 PM, David Hildenbrand wrote:
>>> Move the Multiple-epoch facility handling into it and rename it to
>> [..]
>>
>>
>>> @@ -1055,13 +1057,7 @@ static int kvm_s390_get_tod_ext(struct kvm *kvm, struct kvm_device_attr *attr)
>>>  {
>>>  	struct kvm_s390_vm_tod_clock gtod;
>>>  
>>> -	memset(&gtod, 0, sizeof(gtod));
>>
>> We should keep the memset, otherwise the padding might leak kernel info as we copy .
>> (found by smatch)
> 
> Thanks for the info and running the checker.
> 
> @Janosch please tell me if I should resend!

I'll fix that, no need to resend.

> 
>>
>>
>>     arch/s390/kvm/kvm-s390.c:1068 kvm_s390_get_tod_ext() warn: check that 'gtod' doesn't leak information (struct has a hole after 'epoch_idx')
>>
>>
>>> -
>>> -	if (test_kvm_facility(kvm, 139))
>>> -		kvm_s390_get_tod_clock_ext(kvm, &gtod);
>>> -	else
>>> -		gtod.tod = kvm_s390_get_tod_clock_fast(kvm);
>>> -
>>> +	kvm_s390_get_tod_clock(kvm, &gtod);
>>>  	if (copy_to_user((void __user *)attr->addr, &gtod, sizeof(gtod)))
>>>  		return -EFAULT;
>>>  
>>>
>>
> 
>

Attachment: signature.asc
Description: OpenPGP digital signature