Re: [dpdk-stable] [PATCH v3 1/1] fbarray: get fbarrays from containerized secondary

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 11-Jul-19 12:57 PM, Yasufumi Ogawa wrote:
> On 2019/07/11 19:53, Burakov, Anatoly wrote:
>> On 11-Jul-19 11:31 AM, yasufum.o@gmail.com wrote:
>>> From: Yasufumi Ogawa <ogawa.yasufumi@lab.ntt.co.jp>
>>>
>> <...>
>>
>>> +    if (getpid() == 1) {
>>> +        FILE *hn_fp;
>>> +        hn_fp = fopen("/etc/hostname", "r");
>>> +        if (hn_fp == NULL) {
>>> +            RTE_LOG(ERR, EAL,
>>> +                "Cannot open '/etc/hostname' for secondary\n");
>>> +            return -1;
>>> +        }
>>> +
>>> +        /* with docker, /etc/hostname just has one entry of hostname */
>>> +        if (fscanf(hn_fp, "%s", proc_id) == EOF) {
>>
>> Apologies for not pointing this out earlier, but do i understand 
>> correctly that there's no bounds checking here, and fscanf() will 
>> write however many bytes it wants?
> I understand "%s" is not appropriate. hostname is 12 bytes char and I 
> thought proc_id[16] is enough, but it is unsafe. In addition, hostname 
> can be defined by user with docker's option, so it should be enough for 
> user defined name.
> 
> How do you think expecting max 32 chars of hostname and set boundary 
> "%32s" as following?
> 
>      proc_id[33];  /* define proc id from hostname less than 33 bytes. */
>      ...
>      if (fscanf(hn_fp, "%32s", proc_id) == EOF) {
> 

As long as it takes NULL-termination into account as well, it should be 
OK. I can't recall off the top of my head if %32s includes NULL 
terminator (probably not?).

-- 
Thanks,
Anatoly