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

[Ogawa Yasufumi <yasufum.o@gmail.com>]

2019年7月12日(金) 11:22 Yasufumi Ogawa <yasufum.o@gmail.com>:

> On 2019/07/11 22:14, Burakov, Anatoly wrote:
> > 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?).
> Do you agree if initialize with NULL chars to ensure proc_id is
> NULL-terminated? As tested on my environment, "%Ns" sets next of Nth
> char as NULL, but it seems more reliable.
>      proc_id[33] = { 0 };
>
Hi Anatoly,

I would like to send v4 patch if it is agreeable.

>
> Yasufumi
>