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Date:   Mon, 17 Aug 2020 12:24:29 -0700
From:   Kees Cook <keescook@chromium.org>
To:     "Eric W. Biederman" <ebiederm@xmission.com>
Cc:     Alexander Popov <alex.popov@linux.com>,
        Jann Horn <jannh@google.com>, Will Deacon <will@kernel.org>,
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        Alexander Potapenko <glider@google.com>,
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        Pekka Enberg <penberg@kernel.org>,
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        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
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Subject: Re: [PATCH RFC 2/2] lkdtm: Add heap spraying test
Message-ID: <202008171222.3F206231E@keescook>
References: <20200813151922.1093791-1-alex.popov@linux.com>
 <20200813151922.1093791-3-alex.popov@linux.com>
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On Mon, Aug 17, 2020 at 01:24:37PM -0500, Eric W. Biederman wrote:
> Alexander Popov <alex.popov@linux.com> writes:
> 
> > Add a simple test for CONFIG_SLAB_QUARANTINE.
> >
> > It performs heap spraying that aims to reallocate the recently freed heap
> > object. This technique is used for exploiting use-after-free
> > vulnerabilities in the kernel code.
> >
> > This test shows that CONFIG_SLAB_QUARANTINE breaks heap spraying
> > exploitation technique.
> >
> > Signed-off-by: Alexander Popov <alex.popov@linux.com>
> 
> Why put this test in the linux kernel dump test module?
> 
> I have no problem with tests, and I may be wrong but this
> does not look like you are testing to see if heap corruption
> triggers a crash dump.  Which is what the rest of the tests
> in lkdtm are about.  Seeing if the test triggers successfully
> triggers a crash dump.

The scope of LKDTM has shifted a bit, and I'm fine with tests that
don't cause crashes as long as they're part of testing system-wide
defenses, etc. It's easier to collect similar tests together (even if
they don't break the system).

-- 
Kees Cook