linux-kernel - Re: [PATCH 1/2] selftests/lkdtm: add config and turn off CFI_FORWARD

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Message-ID: <8049e2a9-a478-4c6a-afcd-3aa4434a0590@collabora.com>
Date:   Thu, 14 Apr 2022 16:31:42 +0500
From:   Muhammad Usama Anjum <usama.anjum@...labora.com>
To:     Kees Cook <keescook@...omium.org>, Shuah Khan <shuah@...nel.org>,
        linux-kselftest@...r.kernel.org
Cc:     usama.anjum@...labora.com, kernel@...labora.com,
        kernelci@...ups.io,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] selftests/lkdtm: add config and turn off
 CFI_FORWARD_PROTO

Any thoughts?

On 3/10/22 10:21 PM, Muhammad Usama Anjum wrote:
> On 3/10/22 12:22 AM, Kees Cook wrote:
>> On Fri, Feb 18, 2022 at 01:56:19AM +0500, Muhammad Usama Anjum wrote:
>>> Add config options which are needed for LKDTM sub-tests.
>>> STACKLEAK_ERASING test needs GCC_PLUGIN_STACKLEAK config.
>>> READ_AFTER_FREE and READ_BUDDY_AFTER_FREE tests need
>>> INIT_ON_FREE_DEFAULT_ON config.
>>>
>>> CFI_FORWARD_PROTO always fails as there is no active CFI system of some
>>> kind. Turn it off for now by default until proper support.
>>
>> Building under LTO Clang on arm64, this is available. What's the right
>> way to add a CONFIG that isn't always available?
>>
>> -Kees
> Yeah, as you had mentioned
> (https://github.com/kernelci/kernelci-project/issues/84#issuecomment-1042015431):
> 
> CFI_FORWARD_PROTO is going to fail unless there is an active CFI system
> in place of some kind. Right now this depends on arm64+Clang. In the
> future, this will be arch-agnostic+Clang, but for the moment, it should
> be safe to exclude this test.
> 
> In this patch, I'm turning off CFI_FORWARD_PROTO by default here. We can
> re-enable it when it becomes arch agnostic. CFI_FORWARD_PROTO cannot be
> turned off by using a config. Please let me know your thoughts otherwise.
> 

-- 
Muhammad Usama Anjum