linux-kernel - Re: [PATCH 01/27] modpost: use snprintf() instead of sprintf() for safety

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Date:   Mon, 25 Apr 2022 11:11:17 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        Michal Marek <michal.lkml@...kovi.net>
Subject: Re: [PATCH 01/27] modpost: use snprintf() instead of sprintf() for safety

On Sun, Apr 24, 2022 at 12:09 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> Use snprintf() to avoid the potential buffer overflow, and also
> check the return value to detect the too long path.
>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>

> ---
>
>  scripts/mod/modpost.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 522d5249d196..141370ebbfd3 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -2560,6 +2560,7 @@ int main(int argc, char **argv)
>
>         for (mod = modules; mod; mod = mod->next) {
>                 char fname[PATH_MAX];
> +               int ret;
>
>                 if (mod->is_vmlinux || mod->from_dump)
>                         continue;
> @@ -2578,7 +2579,12 @@ int main(int argc, char **argv)
>                 add_moddevtable(&buf, mod);
>                 add_srcversion(&buf, mod);
>
> -               sprintf(fname, "%s.mod.c", mod->name);
> +               ret = snprintf(fname, sizeof(fname), "%s.mod.c", mod->name);
> +               if (ret >= sizeof(fname)) {
> +                       error("%s: too long path was truncated\n", fname);
> +                       continue;
> +               }
> +
>                 write_if_changed(&buf, fname);
>         }
>
> --
> 2.32.0
>


-- 
Thanks,
~Nick Desaulniers