linux-kernel - Re: [PATCH v2 1/1] selinux: fix another double free

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Message-ID: <CAFqZXNtPjzh2OPaLkMfV_b=-=uU7Z0887-sWUjSG2YJ8e1ucfg@mail.gmail.com>
Date:   Fri, 12 Jun 2020 09:51:00 +0200
From:   Ondrej Mosnacek <omosnace@...hat.com>
To:     Tom Rix <trix@...hat.com>
Cc:     Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Eric Paris <eparis@...isplace.org>,
        Wei Yongjun <weiyongjun1@...wei.com>,
        SElinux list <selinux@...r.kernel.org>,
        Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/1] selinux: fix another double free

On Thu, Jun 11, 2020 at 10:48 PM <trix@...hat.com> wrote:
[...]
> diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c
> index da94a1b4bfda..d0d6668709f0 100644
> --- a/security/selinux/ss/conditional.c
> +++ b/security/selinux/ss/conditional.c
> @@ -392,26 +392,21 @@ static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
>
>                 rc = next_entry(buf, fp, sizeof(u32) * 2);
>                 if (rc)
> -                       goto err;
> +                       return rc;
>
>                 expr->expr_type = le32_to_cpu(buf[0]);
>                 expr->bool = le32_to_cpu(buf[1]);
>
>                 if (!expr_node_isvalid(p, expr)) {
>                         rc = -EINVAL;
> -                       goto err;
> +                       return rc;
>                 }

Sorry for more nitpicking... This can be further simplified to just
"return -EINVAL;" and the braces can be removed.

>         }
>
>         rc = cond_read_av_list(p, fp, &node->true_list, NULL);
>         if (rc)
> -               goto err;
> +               return rc;
>         rc = cond_read_av_list(p, fp, &node->false_list, &node->true_list);
> -       if (rc)
> -               goto err;
> -       return 0;
> -err:
> -       cond_node_destroy(node);
>         return rc;

Also here you can skip the rc assignment:

return cond_read_av_list(p, fp, &node->false_list, &node->true_list);

>  }
>
> --
> 2.18.1

--
Ondrej Mosnacek
Software Engineer, Platform Security - SELinux kernel
Red Hat, Inc.