linux-kernel - Re: [PATCH bpf-next] selftests/bpf: Fix strncpy() fortify warning

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAEf4Bzbq0PSsc6xCGSF=Af-pcysjt8Lv76-4N65AJMpXOOpOcg@mail.gmail.com>
Date:   Thu, 27 Oct 2022 13:09:57 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Rong Tao <rtoax@...mail.com>
Cc:     Rong Tao <rongtao@...tc.cn>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>,
        "open list:BPF [GENERAL] (Safe Dynamic Programs and Tools)" 
        <bpf@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next] selftests/bpf: Fix strncpy() fortify warning

On Thu, Oct 27, 2022 at 4:34 AM Rong Tao <rtoax@...mail.com> wrote:
>
> From: Rong Tao <rongtao@...tc.cn>
>
> Compile samples/bpf, error:
> $ cd samples/bpf
> $ make
> ...
> In function ‘__enable_controllers’:
> samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:80:17: warning: ‘strncpy’ specified bound 4097 equals destination size [-Wstringop-truncation]
>    80 |                 strncpy(enable, controllers, sizeof(enable));
>       |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Signed-off-by: Rong Tao <rongtao@...tc.cn>
> ---
>  tools/testing/selftests/bpf/cgroup_helpers.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c
> index e914cc45b766..a70e873b267e 100644
> --- a/tools/testing/selftests/bpf/cgroup_helpers.c
> +++ b/tools/testing/selftests/bpf/cgroup_helpers.c
> @@ -77,7 +77,7 @@ static int __enable_controllers(const char *cgroup_path, const char *controllers
>                 enable[len] = 0;
>                 close(fd);
>         } else {
> -               strncpy(enable, controllers, sizeof(enable));
> +               strncpy(enable, controllers, sizeof(enable) - 1);

enable is not initialized, so we might end up with non-zero-terminated
string. Let's enable[0] = '\0'; at the beginning and then strncat()
here?

>         }
>
>         snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
> --
> 2.31.1
>