Re: [PATCH bpf-next 2/2] selftests/bpf: correct path to include msg + path

Song Liu
2019-10-02T16:29:29Z

> On Oct 2, 2019, at 5:04 AM, Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> wrote:
>
> The "path" buf is supposed to contain path + printf msg up to 24 bytes.
> It will be cut anyway, but compiler generates truncation warns like:
>
> "
> samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c: In
> function ‘setup_cgroup_environment’:
> samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:52:34:
> warning: ‘/cgroup.controllers’ directive output may be truncated
> writing 19 bytes into a region of size between 1 and 4097
> [-Wformat-truncation=]
> snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path);
> ^~~~~~~~~~~~~~~~~~~
> samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:52:2:
> note: ‘snprintf’ output between 20 and 4116 bytes into a destination
> of size 4097
> snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:72:34:
> warning: ‘/cgroup.subtree_control’ directive output may be truncated
> writing 23 bytes into a region of size between 1 and 4097
> [-Wformat-truncation=]
> snprintf(path, sizeof(path), "%s/cgroup.subtree_control",
> ^~~~~~~~~~~~~~~~~~~~~~~
> cgroup_path);
> samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:72:2:
> note: ‘snprintf’ output between 24 and 4120 bytes into a destination
> of size 4097
> snprintf(path, sizeof(path), "%s/cgroup.subtree_control",
> cgroup_path);
> "
>
> In order to avoid warns, lets decrease buf size for cgroup workdir on
> 24 bytes with assumption to include also "/cgroup.subtree_control" to
> the address. The cut will never happen anyway.
>
> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>

Acked-by: Song Liu <songliubraving@fb.com>