Re: [PATCH] tracing: Consider the NULL character when validating the event length

[Leo Yan]

On 10/7/24 15:22, Steven Rostedt wrote:
> Warning: EXTERNAL SENDER, use caution when opening links or attachments.
>
>
> On Mon,  7 Oct 2024 14:51:26 +0100
> Leo Yan <leo.yan@xxxxxxx> wrote:
>
> > strlen() returns a string length excluding the null byte. This commit
> > adds 1 to account for the NULL terminating character when checking if an
> > event string is within the maximum length.
> >
> > Fixes: dec65d79fd26 ("tracing/probe: Check event name length correctly")
> > Signed-off-by: Leo Yan <leo.yan@xxxxxxx>
> > ---
> >   kernel/trace/trace_probe.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> > index 39877c80d6cb..376ba56c3680 100644
> > --- a/kernel/trace/trace_probe.c
> > +++ b/kernel/trace/trace_probe.c
> > @@ -276,7 +276,7 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
> >                }
> >                trace_probe_log_err(offset, NO_EVENT_NAME);
> >                return -EINVAL;
> > -     } else if (len > MAX_EVENT_NAME_LEN) {
> > +     } else if (len + 1 > MAX_EVENT_NAME_LEN) {
>
> Usually, the check is:
>
>          } else if (len >= MAX_EVENT_NAME_LEN) {
>
> Which is a better way to check max length.

Will update. Thanks for suggestion.

Leo