On Fri, Jul 24, 2020 at 2:07 AM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote:
>
> For probing program and map types, bpftool loops on type values and uses
> the relevant type name in prog_type_name[] or map_type_name[]. To ensure
> the name exists, we exit from the loop if we go over the size of the
> array.
>
> However, this is not enough in the case where the arrays have "holes" in
> them, program or map types for which they have no name, but not at the
> end of the list. This is currently the case for BPF_PROG_TYPE_LSM, not
> known to bpftool and which name is a null string. When probing for
> features, bpftool attempts to strlen() that name and segfaults.
>
> Let's fix it by skipping probes for "unknown" program and map types,
> with an informational message giving the numeral value in that case.
>
> Fixes: 93a3545d812a ("tools/bpftool: Add name mappings for SK_LOOKUP prog and attach type")
> Reported-by: Paul Chaignon <paul@xxxxxxxxx>
> Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Acked-by: Song Liu <songliubraving@xxxxxx>
