On Mon, Apr 12, 2021 at 8:38 AM Florent Revest <revest@xxxxxxxxxxxx> wrote: > > This exercises most of the format specifiers. > > Signed-off-by: Florent Revest <revest@xxxxxxxxxxxx> > Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > --- As I mentioned on another patch, we probably need negative tests even more than positive ones. I think an easy and nice way to do this is to have a separate BPF skeleton where fmt string and arguments are provided through read-only global variables, so that user-space can re-use the same BPF skeleton to simulate multiple cases. BPF program itself would just call bpf_snprintf() and store the returned result. Whether we need to validate the verifier log is up to debate (though it's not that hard to do by overriding libbpf_print_fn() callback), I'd be ok at least knowing that some bad format strings are rejected and don't crash the kernel. > .../selftests/bpf/prog_tests/snprintf.c | 81 +++++++++++++++++++ > .../selftests/bpf/progs/test_snprintf.c | 74 +++++++++++++++++ > 2 files changed, 155 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf.c > create mode 100644 tools/testing/selftests/bpf/progs/test_snprintf.c > [...]
