Re: [dpdk-dev] [PATCH v3 0/4] Memory corruption due to HW rings allocation

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 5/18/2020 10:48 AM, Renata Saiakhova wrote:
> Hi Ferruh,
> 
> thanks for comments,
> 
> are the rte_eth_dma_zone_reserve() calls always used to allocate HW rings? It is
> not totally clear to me. That was partly the reason I don't do the fix for every
> driver which uses this API. I made fixes in the drivers which uses the same
> pattern to allocate / release queues, for other drivers I was not sure but
> anyway I couldn't spend more time for further investigations. In the company I
> work for we use dpdk for our project and maintain it in separate tree, and the
> vulnerability with HW rings is a real issue for igb and ixgbe drivers and needs
> to be fixed. Therefore I would like this patch to be accepted in order to not
> maintain the fix ourselves. But unfortunately I don't have resources (e.g. time)
> to fix the issue for all the drivers, because, as I mentioned, they are not
> following the same pattern to release their queues. So my proposal is that I fix
> it in this patch in a number of drivers (including igb, ixgbe and i40e) and
> others can take over and improve other drivers, if they see the same issue. This
> is also a reason why the drivers' changes are not in one commit for all the drivers.
> 
> For the proposal adding pmd name as prefix to queue memzone name or update
> the 'rte_eth_dma_zone_reserve()' to check the size & alignment instead of just a
> name, I don't know, as an external person, how sensitive dpdk project to change
> an internal API and existing code (the call should be changed in all the
> drivers). But anyway, I think the real problem is more an absence of memzone
> pointer, and in long term it should be solved in this way, rather than search by
> name.

Hi Renata,

'rte_eth_dma_zone_reserve()' returning existing memzone just based on 'name'
without checking the size, alignment, socket_id seems wrong to me, let me check
it, it shouldn't be hard to update.

But even 'rte_eth_dma_zone_reserve()' checks won't be enough (what to do if
check fails and not returns a memzone?), the proper solution is PMD free the
memzone as they removed, as done in this patch.

Also I suggested prefixing the memzone name as workaround but instead we can go
with this patchset with the implemented PMDs and other PMD owners can implement
the free when they need instead of workaround.

There is a comment from Wie to add more frees to i40e, and there is another from
Jeff on 'rte_eth_dma_zone_free()' return type, can you please check them? So we
can proceed with this patch for the release.

Thanks,
ferruh

> 
> Kind regards,
> Renata
> --------------------------------------------------------------------------------
> *From:* Ferruh Yigit <ferruh.yigit@intel.com>
> *Sent:* Wednesday, May 13, 2020 5:22 PM
> *To:* Renata Saiakhova <renata.saiakhova@ekinops.com>; dev@dpdk.org <dev@dpdk.org>
> *Cc:* Anatoly Burakov <anatoly.burakov@intel.com>; Thomas Monjalon
> <thomas@monjalon.net>; Neil Horman <nhorman@tuxdriver.com>
> *Subject:* Re: [dpdk-dev] [PATCH v3 0/4] Memory corruption due to HW rings
> allocation
>  
> On 5/13/2020 2:14 PM, Renata Saiakhova wrote:
>> igb and ixgbe and some other drivers allocate HW rings using rte_eth_dma_zone_reserve(),
>> which checks first if the memzone exists for a given name, consisting of port
>> id, queue_id, rx/tx direction, but not for the size, alignment, and socket_id.
>> If the memzone with a given name exists it is returned, otherwise it is
>> allocated.
>> Disconnecting dpdk port from one type of interface (igb) and connecting it
>> to another type of interface (ixgbe) for the same port id, potentially creates
>> memory overlap and corruption, because it may require memzone of bigger size.
>> That's what is happening from switching from igb to ixgbe having the same port
>> id.
>> 
>> v2->v3: Remove #undef ETH_DMA_MZONE_NAME and minor changes in code standard
>> v1->v2: Minor changes on code standard and additional fixes in i40e em and ice drivers
>> 
>> Renata Saiakhova (4):
>>   librte_ethdev: Introduce a function to release HW rings
>>   drivers/net: Fix in igb and ixgbe HW rings memory
>>   drivers/net: Fix in i40e HW rings memory overlap
>>   drivers/net: Fix in em and ice HW rings memory overlap
> 
> I think all driver patches can be squashed into single patch, overall they are
> implementing same logic.
> 
> But as mentioned before, there are multiple other drivers allocating HW rings
> with exact same name. At least I can see:
> iavf
> nfp
> fm10k
> axgbe
> 
> Or how can we know if a new PMD won't cause exact same behavior? What to you
> think adding pmd name as prefix to queue memzone name for all PMDs? This can
> help new PMDs using existing code as sample.
> 
> I don't know if it has been discussed before, but wouldn't update the
> 'rte_eth_dma_zone_reserve()' to check the size & alignment instead of just name
> fix the issue for all drivers without needing to update them?