Re: [PATCH bpf-next] selftests/bpf: Fix issues in parse_num_list()

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Mon, Apr 4, 2022 at 9:45 AM Yuntao Wang <ytcoode@gmail.com> wrote:
>
> There are some issues in parse_num_list():
>
> 1. The end variable is assigned twice when parsing_end is true.
> 2. The function does not check that parsing_end should finally be false.
>
> Clean up parse_num_list() and fix these issues.

It would be great to also explain user-visible bug. What do you do to
trigger bugs? Can you please put that into the commit message, in a
before/after fashion? Thanks!

>
> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> ---
>  tools/testing/selftests/bpf/testing_helpers.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c
> index 795b6798ccee..82f0e2d99c23 100644
> --- a/tools/testing/selftests/bpf/testing_helpers.c
> +++ b/tools/testing/selftests/bpf/testing_helpers.c
> @@ -20,16 +20,16 @@ int parse_num_list(const char *s, bool **num_set, int *num_set_len)
>                 if (errno)
>                         return -errno;
>
> -               if (parsing_end)
> -                       end = num;
> -               else
> +               if (!parsing_end) {
>                         start = num;
> +                       if (*next == '-') {
> +                               s = next + 1;
> +                               parsing_end = true;
> +                               continue;
> +                       }
> +               }
>
> -               if (!parsing_end && *next == '-') {
> -                       s = next + 1;
> -                       parsing_end = true;
> -                       continue;
> -               } else if (*next == ',') {
> +               if (*next == ',') {
>                         parsing_end = false;
>                         s = next + 1;
>                         end = num;
> @@ -60,7 +60,7 @@ int parse_num_list(const char *s, bool **num_set, int *num_set_len)
>                         set[i] = true;
>         }
>
> -       if (!set)
> +       if (!set || parsing_end)
>                 return -EINVAL;
>
>         *num_set = set;
> --
> 2.35.1
>