On Thu, Dec 15, 2022 at 11:02 AM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> On Thu, 15 Dec 2022 10:31:50 -0800
> Ian Rogers <irogers@xxxxxxxxxx> wrote:
>
> > Computing the address from a NULL pointer results in undefined behavior
> > which things like undefined behavior sanitizer promote into real
> > failures.
>
> I thought commit aff006d4af0c7 ("libtracefs: Do not initialize with NULL
> offsets") was suppose to fix this.
It may have done, sorry for not keeping track. I went to my libtracefs
git repo to fix the patch 2 issue and saw that this change didn't
vanish with a rebase.
> Oh, I think I may have forgotten to remove the check against dynevent!
>
> Does this work instead?
>
> -- Steve
>
> diff --git a/src/tracefs-dynevents.c b/src/tracefs-dynevents.c
> index 48bb26a96c58..7a3c45ce25a3 100644
> --- a/src/tracefs-dynevents.c
> +++ b/src/tracefs-dynevents.c
> @@ -713,9 +713,6 @@ dynevent_info(struct tracefs_dynevent *dynevent, char **system,
> &dynevent->address, &dynevent->format };
> int i;
>
> - if (!dynevent)
> - return TRACEFS_DYNEVENT_UNKNOWN;
> -
I think the issue is above in &dynevent->... that dynevent may be
NULL. It seems from removing this that dynevent can't be NULL and so
the undefined behavior can never happen - in which case there's no
issue to fix and the test is unnecessary and should be removed. That's
a long winded way of saying I think that's a correct patch and this
patch is unnecessary :-)
Thanks,
Ian
> for (i = 0; i < ARRAY_SIZE(lv); i++) {
> if (lv[i]) {
> if (*rv[i]) {
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