Re: [PATCH v2] net/tap: resolve stringop-overflow with gcc 12 on ppc64le

[David Christensen <drc@linux.vnet.ibm.com>]

On 9/29/23 6:48 AM, Ferruh Yigit wrote:
> On 6/7/2023 7:47 PM, Ferruh Yigit wrote:
>> On 5/16/2023 10:55 AM, Ferruh Yigit wrote:
>>> On 5/16/2023 2:28 AM, Stephen Hemminger wrote:
>>>> On Tue, 16 May 2023 00:35:56 +0100
>>>> Ferruh Yigit <ferruh.yigit@amd.com> wrote:
>>>>
>>>>> Yes only some scripts and possible applications that hotplug tap
>>>>> interface with hardcoded parameters may impacted, don't know how big is
>>>>> this amount but this ends up breaking something that was working before
>>>>> upgrading DPDK for them.
>>>>>
>>>>> And I believe the motivation is weak to break the behavior.
>>>>>
>>>>> Won't it be better to update 'rte_ether_unformat_addr()' to accept more
>>>>> flexible syntax, and use it? Is there any disadvantage of this approach?
>>>>
>>>> It is already more flexible than the standard ether_aton().
>>>
>>> I mean to accept single chars, as 'tap' currently does, like "a:a:a:a:a:a".
>>>
>>> Agree that impact of tap change is small, but if we can eliminate it
>>> completely without any side affect, why not?
>>>
>>>
>>> As accepting single char will be expanding 'rte_ether_unformat_addr()'
>>> capability, it will be backward compatible, am I missing anything?
>>>
>>
>> Hi David,
>>
>> If API update is not planned, what do you think to just solve the build
>> error without changing functionality with a change something like below:
>>
>> ```
>>   -       (strlen(mac_byte) == strspn(mac_byte,
>>   -                       ETH_TAP_CMP_MAC_FMT))) {
>>   +       (strlen(mac_byte) == strspn(mac_byte, ETH_TAP_CMP_MAC_FMT)) &&
>>   +                       index < RTE_ETHER_ADDR_LEN) {
>>
>> ```
> 
> Hi David,
> 
> If you can confirm above fixes the issue, I can send a patch for it.

Confirmed that your proposed change resolves the build issue on ppc64le. 
  Appreciate if you can submit the patch.

Dave