Re: [PATCH v8 4/8] bpftool: Ensure task comm is always NUL-terminated

[Yafang Shao <laoar.shao@gmail.com>]

On Fri, Sep 13, 2024 at 5:14 AM Justin Stitt <justinstitt@google.com> wrote:
>
> Hi,
>
> On Wed, Aug 28, 2024 at 11:03:17AM GMT, Yafang Shao wrote:
> > Let's explicitly ensure the destination string is NUL-terminated. This way,
> > it won't be affected by changes to the source string.
> >
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > Reviewed-by: Quentin Monnet <qmo@kernel.org>
> > ---
> >  tools/bpf/bpftool/pids.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/tools/bpf/bpftool/pids.c b/tools/bpf/bpftool/pids.c
> > index 9b898571b49e..23f488cf1740 100644
> > --- a/tools/bpf/bpftool/pids.c
> > +++ b/tools/bpf/bpftool/pids.c
> > @@ -54,6 +54,7 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
> >               ref = &refs->refs[refs->ref_cnt];
> >               ref->pid = e->pid;
> >               memcpy(ref->comm, e->comm, sizeof(ref->comm));
> > +             ref->comm[sizeof(ref->comm) - 1] = '\0';
>
> ...
>
> >               refs->ref_cnt++;
> >
> >               return;
> > @@ -77,6 +78,7 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
> >       ref = &refs->refs[0];
> >       ref->pid = e->pid;
> >       memcpy(ref->comm, e->comm, sizeof(ref->comm));
> > +     ref->comm[sizeof(ref->comm) - 1] = '\0';
>
> Excuse my ignorance, do we not have a strscpy() equivalent usable in bpf
> code?

To my knowledge, there is no direct equivalent of the standard
strcpy() function available in bpftool or libbpf code.

-- 
Regards
Yafang