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Subject: Re: [PATCH 1/1] selinux: fix double free
To:     Stephen Smalley <stephen.smalley.work@gmail.com>
Cc:     Paul Moore <paul@paul-moore.com>,
        Eric Paris <eparis@parisplace.org>,
        Ondrej Mosnacek <omosnace@redhat.com>,
        Jeffrey Vander Stoep <jeffv@google.com>, rgb@redhat.com,
        SElinux list <selinux@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
References: <20200610181021.19209-1-trix@redhat.com>
 <20200610181021.19209-2-trix@redhat.com>
 <CAEjxPJ4uRG4FiBbyUxQdsLWsz4torr+rst1VKN_Gdk5PqT6Kpw@mail.gmail.com>
From:   Tom Rix <trix@redhat.com>
Message-ID: <5bfa5213-7d1b-684a-9e21-488fcbf14b91@redhat.com>
Date:   Wed, 10 Jun 2020 13:00:35 -0700
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>> +++ b/security/selinux/ss/services.c
>> @@ -2888,8 +2888,12 @@ int security_get_bools(struct selinux_state *state,
>>         if (*names) {
>>                 for (i = 0; i < *len; i++)
>>                         kfree((*names)[i]);
>> +               kfree(names);
> kfree(*names)?

Yes.

> kfree(*values);
>> +       *len = 0;
>> +       *names = NULL;
>> +       *values = NULL;
>>         goto out;
>>  }
> Wondering if the caller handling ought to be changed too even though
> this should avoid the problem.
>
The poisoning of the returns avoids this.