Re: [PATCH 0/5] fix segment fault when parse args

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

On 3/17/2023 2:43 AM, fengchengwen wrote:
> On 2023/3/17 2:18, Ferruh Yigit wrote:
>> On 3/14/2023 12:48 PM, Chengwen Feng wrote:
>>> The rte_kvargs_process() was used to parse KV pairs, it also supports
>>> to parse 'only keys' (e.g. socket_id) type. And the callback function 
>>> parameter 'value' is NULL when parsed 'only keys'.
>>>
>>> It may leads to segment fault when parse args with 'only key', this 
>>> patchset fixes rest of them.
>>>
>>> Chengwen Feng (5):
>>>   app/pdump: fix segment fault when parse args
>>>   net/memif: fix segment fault when parse devargs
>>>   net/pcap: fix segment fault when parse devargs
>>>   net/ring: fix segment fault when parse devargs
>>>   net/sfc: fix segment fault when parse devargs
>>
>> Hi Chengwen,
>>
>> Did you scan all `rte_kvargs_process()` instances?
> 
> No, I was just looking at the modules I was concerned about.
> I looked at it briefly, and some modules had the same problem.
> 
>>
>>
>> And if there would be a way to tell kvargs that a value is expected (or
>> not) this checks could be done in kvargs layer, I think this also can be
>> to look at.
> 
> Yes, the way to tell kvargs may lead to a lot of modifys and also break ABI.
> I also think about just set value = "" when only exist key, It could perfectly solve the above segment scene.
> But it also break the API's behavior.
> 

What about having a new API, like `rte_kvargs_process_extended()`,

That gets an additional flag as parameter, which may have values like
following to indicate if key expects a value or not:
ARG_MAY_HAVE_VALUE  --> "key=value" OR 'key'
ARG_WITH_VALUE      --> "key=value"
ARG_NO_VALUE        --> 'key'

Default flag can be 'ARG_MAY_HAVE_VALUE' and it becomes same as
`rte_kvargs_process()`.

This way instead of adding checks, relevant usage can be replaced by
`rte_kvargs_process_extended()`, this requires similar amount of change
but code will be more clean I think.

Do you think does this work?


> 
> Or continue fix the exist code (about 10+ place more),
> for new invoking, because the 'arg_handler_t' already well documented (52ab17efdecf935792ee1d0cb749c0dbd536c083),
> they'll take the initiative to prevent this.
> 
> 
> Hope for more advise for the next.
> 
>> .
>>