linux-kernel - Re: [PATCH] samples/landlock: fix path

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Date:   Tue, 27 Apr 2021 12:13:50 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Tom Rix <trix@...hat.com>
Cc:     mic@...ikod.net, Nathan Chancellor <nathan@...nel.org>,
        linux-security-module@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] samples/landlock: fix path_list memory leak

On Tue, Apr 27, 2021 at 11:38 AM <trix@...hat.com> wrote:
>
> From: Tom Rix <trix@...hat.com>
>
> Clang static analysis reports this error
>
> sandboxer.c:134:8: warning: Potential leak of memory
>   pointed to by 'path_list'
>         ret = 0;
>               ^
> path_list is allocated in parse_path() but never freed.
>
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  samples/landlock/sandboxer.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
> index 7a15910d2171..4629d011ed61 100644
> --- a/samples/landlock/sandboxer.c
> +++ b/samples/landlock/sandboxer.c
> @@ -134,6 +134,8 @@ static int populate_ruleset(
>         ret = 0;
>
>  out_free_name:
> +       if (path_list)
> +               free(path_list);

I don't think the conditional is even necessary? By our first `goto
out_free_name;`, `parse_path` has already been called/memory for
`path_list` has already been allocated. `parse_path` doesn't check
whether `malloc` has failed.

>         free(env_path_name);
>         return ret;
>  }
> --
> 2.26.3
>


-- 
Thanks,
~Nick Desaulniers