Re: [dpdk-dev] [PATCH] vhost: Fix Segmentation fault of NULL address

["Qiu, Michael" <michael.qiu@intel.com>]

On 3/26/2015 3:52 PM, Xie, Huawei wrote:
> On 3/26/2015 3:05 PM, Qiu, Michael wrote:
>> Function gpa_to_vva() could return zero, while this will lead
>> a Segmentation fault.
>>
>> This patch is to fix this issue.
>>
>> Signed-off-by: Michael Qiu <michael.qiu@intel.com>
>> ---
>>  lib/librte_vhost/vhost_rxtx.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
>> index 535c7a1..23c8acb 100644
>> --- a/lib/librte_vhost/vhost_rxtx.c
>> +++ b/lib/librte_vhost/vhost_rxtx.c
>> @@ -587,6 +587,9 @@ rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
>>  
>>  		/* Buffer address translation. */
>>  		vb_addr = gpa_to_vva(dev, desc->addr);
>> +		if (!vb_addr)
>> +			return entry_success;
>> +
> Firstly we should add check for all gpa_to_vva translation, and do
> reporting and cleanup on error. We should avoid the case that some buggy
> or malicious guest virtio driver gives us an invalid GPA(for example,
> GPA for some MMIO space) and crash our vhost process.

Yes, agree, I will do this for next version.

> As we discuss, you meet segfault here, but our virtio PMD shouldn't give
> us the GPA that has no translation, so we should root cause first and

Yes, root cause is very important, but it will spend lots time, and I
think we could be possible to apply this first(All check version).

Thanks,
Michael
> fix the problem, and then submit the patch checking all gpa_to_vva
> translation.
>
> -Huawei
>>  		/* Prefetch buffer address. */
>>  		rte_prefetch0((void *)(uintptr_t)vb_addr);
>>  
>