linux-kernel - Re: [PATCH linux-kselftest/test v1] apparmor: add AppArmor KUnit tests for policy unpack

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Message-ID: <201910301157.58D0CE4D3@keescook>
Date:   Wed, 30 Oct 2019 11:59:00 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Iurii Zaikin <yzaikin@...gle.com>
Cc:     Brendan Higgins <brendanhiggins@...gle.com>,
        shuah <shuah@...nel.org>, john.johansen@...onical.com,
        jmorris@...ei.org, serge@...lyn.com, alan.maguire@...cle.com,
        davidgow@...gle.com, Luis Chamberlain <mcgrof@...nel.org>,
        Theodore Ts'o <tytso@....edu>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-security-module@...r.kernel.org,
        KUnit Development <kunit-dev@...glegroups.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        Mike Salvatore <mike.salvatore@...onical.com>
Subject: Re: [PATCH linux-kselftest/test v1] apparmor: add AppArmor KUnit
 tests for policy unpack

On Thu, Oct 17, 2019 at 05:33:56PM -0700, Iurii Zaikin wrote:
> On Thu, Oct 17, 2019 at 5:19 PM Brendan Higgins
> <brendanhiggins@...gle.com> wrote:
> 
> > +config SECURITY_APPARMOR_TEST
> > +       bool "Build KUnit tests for policy_unpack.c"
> > +       default n

New options already already default n, this can be left off.

> > +       depends on KUNIT && SECURITY_APPARMOR
> > +       help
> >
> select SECURITY_APPARMOR ?

"select" doesn't enforce dependencies, so just a "depends ..." is
correct.

> > +       KUNIT_EXPECT_EQ(test, size, TEST_BLOB_DATA_SIZE);
> > +       KUNIT_EXPECT_TRUE(test,
> > +               memcmp(blob, TEST_BLOB_DATA, TEST_BLOB_DATA_SIZE) == 0);
> I think this must be  KUNIT_ASSERT_EQ(test, size, TEST_BLOB_DATA_SIZE);,
> otherwise there could be a buffer overflow in memcmp. All tests that
> follow such pattern

Agreed.

> are suspect. Also, not sure about your stylistic preference for
> KUNIT_EXPECT_TRUE(test,
>                memcmp(blob, TEST_BLOB_DATA, TEST_BLOB_DATA_SIZE) == 0);
> vs
> KUNIT_EXPECT_EQ(test,
>                0,
>                memcmp(blob, TEST_BLOB_DATA, TEST_BLOB_DATA_SIZE));

I like == 0.

-- 
Kees Cook