2022-02-17 23:03:03

by Muhammad Usama Anjum

[permalink] [raw]
Subject: [PATCH 1/2] selftests/lkdtm: add config and turn off CFI_FORWARD_PROTO

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.

Cc: Kees Cook <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Fixes: 46d1a0f03d66 ("selftests/lkdtm: Add tests for LKDTM targets")
Signed-off-by: Muhammad Usama Anjum <[email protected]>
---
tools/testing/selftests/lkdtm/config | 2 ++
tools/testing/selftests/lkdtm/tests.txt | 2 +-
2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/lkdtm/config b/tools/testing/selftests/lkdtm/config
index 46f39ee762086..adc9fa60057c5 100644
--- a/tools/testing/selftests/lkdtm/config
+++ b/tools/testing/selftests/lkdtm/config
@@ -2,8 +2,10 @@ CONFIG_LKDTM=y
CONFIG_DEBUG_LIST=y
CONFIG_SLAB_FREELIST_HARDENED=y
CONFIG_FORTIFY_SOURCE=y
+CONFIG_GCC_PLUGIN_STACKLEAK=y
CONFIG_HARDENED_USERCOPY=y
CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
+CONFIG_INIT_ON_FREE_DEFAULT_ON=y
CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
CONFIG_UBSAN=y
CONFIG_UBSAN_BOUNDS=y
diff --git a/tools/testing/selftests/lkdtm/tests.txt b/tools/testing/selftests/lkdtm/tests.txt
index 6b36b7f5dcf96..aa947b0ce1eeb 100644
--- a/tools/testing/selftests/lkdtm/tests.txt
+++ b/tools/testing/selftests/lkdtm/tests.txt
@@ -72,7 +72,7 @@ USERCOPY_STACK_FRAME_FROM
USERCOPY_STACK_BEYOND
USERCOPY_KERNEL
STACKLEAK_ERASING OK: the rest of the thread stack is properly erased
-CFI_FORWARD_PROTO
+#CFI_FORWARD_PROTO
FORTIFIED_STRSCPY
FORTIFIED_OBJECT
FORTIFIED_SUBOBJECT
--
2.30.2


2022-02-17 23:59:02

by Muhammad Usama Anjum

[permalink] [raw]
Subject: [PATCH 2/2] selftests/lkdtm: add config

Add config option which is needed for SLAB_LINEAR_OVERFLOW test. It
needs KASAN enabled.

Cc: Kees Cook <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Fixes: 9c4f6ebc3665 ("lkdtm/heap: Add vmalloc linear overflow test")
Signed-off-by: Muhammad Usama Anjum <[email protected]>
---
tools/testing/selftests/lkdtm/config | 1 +
1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/lkdtm/config b/tools/testing/selftests/lkdtm/config
index adc9fa60057c5..4e8af0f712f74 100644
--- a/tools/testing/selftests/lkdtm/config
+++ b/tools/testing/selftests/lkdtm/config
@@ -7,6 +7,7 @@ CONFIG_HARDENED_USERCOPY=y
CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
CONFIG_INIT_ON_FREE_DEFAULT_ON=y
CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
+CONFIG_KASAN=y
CONFIG_UBSAN=y
CONFIG_UBSAN_BOUNDS=y
CONFIG_UBSAN_TRAP=y
--
2.30.2

2022-02-18 15:53:45

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH 1/2] selftests/lkdtm: add config and turn off CFI_FORWARD_PROTO

On 2/18/22 1:56 AM, 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.
>
> Cc: Kees Cook <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
> Fixes: 46d1a0f03d66 ("selftests/lkdtm: Add tests for LKDTM targets")
> Signed-off-by: Muhammad Usama Anjum <[email protected]>
Reported-by: "kernelci.org bot" <[email protected]>

2022-02-18 16:16:05

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH 2/2] selftests/lkdtm: add config

On 2/18/22 1:56 AM, Muhammad Usama Anjum wrote:
> Add config option which is needed for SLAB_LINEAR_OVERFLOW test. It
> needs KASAN enabled.
>
> Cc: Kees Cook <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
> Fixes: 9c4f6ebc3665 ("lkdtm/heap: Add vmalloc linear overflow test")
> Signed-off-by: Muhammad Usama Anjum <[email protected]>
Reported-by: "kernelci.org bot" <[email protected]>

2022-02-28 09:49:33

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH 1/2] selftests/lkdtm: add config and turn off CFI_FORWARD_PROTO

Hi,

Any thoughts?

On 2/18/22 1:56 AM, 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.
>
> Cc: Kees Cook <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
> Fixes: 46d1a0f03d66 ("selftests/lkdtm: Add tests for LKDTM targets")
> Signed-off-by: Muhammad Usama Anjum <[email protected]>
> ---
> tools/testing/selftests/lkdtm/config | 2 ++
> tools/testing/selftests/lkdtm/tests.txt | 2 +-
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/lkdtm/config b/tools/testing/selftests/lkdtm/config
> index 46f39ee762086..adc9fa60057c5 100644
> --- a/tools/testing/selftests/lkdtm/config
> +++ b/tools/testing/selftests/lkdtm/config
> @@ -2,8 +2,10 @@ CONFIG_LKDTM=y
> CONFIG_DEBUG_LIST=y
> CONFIG_SLAB_FREELIST_HARDENED=y
> CONFIG_FORTIFY_SOURCE=y
> +CONFIG_GCC_PLUGIN_STACKLEAK=y
> CONFIG_HARDENED_USERCOPY=y
> CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
> +CONFIG_INIT_ON_FREE_DEFAULT_ON=y
> CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
> CONFIG_UBSAN=y
> CONFIG_UBSAN_BOUNDS=y
> diff --git a/tools/testing/selftests/lkdtm/tests.txt b/tools/testing/selftests/lkdtm/tests.txt
> index 6b36b7f5dcf96..aa947b0ce1eeb 100644
> --- a/tools/testing/selftests/lkdtm/tests.txt
> +++ b/tools/testing/selftests/lkdtm/tests.txt
> @@ -72,7 +72,7 @@ USERCOPY_STACK_FRAME_FROM
> USERCOPY_STACK_BEYOND
> USERCOPY_KERNEL
> STACKLEAK_ERASING OK: the rest of the thread stack is properly erased
> -CFI_FORWARD_PROTO
> +#CFI_FORWARD_PROTO
> FORTIFIED_STRSCPY
> FORTIFIED_OBJECT
> FORTIFIED_SUBOBJECT

2022-03-08 11:43:46

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH 1/2] selftests/lkdtm: add config and turn off CFI_FORWARD_PROTO

Reminder!

On 2/28/22 12:06 PM, Muhammad Usama Anjum wrote:
> Hi,
>
> Any thoughts?
>
> On 2/18/22 1:56 AM, 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.
>>
>> Cc: Kees Cook <[email protected]>
>> Cc: Greg Kroah-Hartman <[email protected]>
>> Fixes: 46d1a0f03d66 ("selftests/lkdtm: Add tests for LKDTM targets")
>> Signed-off-by: Muhammad Usama Anjum <[email protected]>
>> ---
>> tools/testing/selftests/lkdtm/config | 2 ++
>> tools/testing/selftests/lkdtm/tests.txt | 2 +-
>> 2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/lkdtm/config b/tools/testing/selftests/lkdtm/config
>> index 46f39ee762086..adc9fa60057c5 100644
>> --- a/tools/testing/selftests/lkdtm/config
>> +++ b/tools/testing/selftests/lkdtm/config
>> @@ -2,8 +2,10 @@ CONFIG_LKDTM=y
>> CONFIG_DEBUG_LIST=y
>> CONFIG_SLAB_FREELIST_HARDENED=y
>> CONFIG_FORTIFY_SOURCE=y
>> +CONFIG_GCC_PLUGIN_STACKLEAK=y
>> CONFIG_HARDENED_USERCOPY=y
>> CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
>> +CONFIG_INIT_ON_FREE_DEFAULT_ON=y
>> CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
>> CONFIG_UBSAN=y
>> CONFIG_UBSAN_BOUNDS=y
>> diff --git a/tools/testing/selftests/lkdtm/tests.txt b/tools/testing/selftests/lkdtm/tests.txt
>> index 6b36b7f5dcf96..aa947b0ce1eeb 100644
>> --- a/tools/testing/selftests/lkdtm/tests.txt
>> +++ b/tools/testing/selftests/lkdtm/tests.txt
>> @@ -72,7 +72,7 @@ USERCOPY_STACK_FRAME_FROM
>> USERCOPY_STACK_BEYOND
>> USERCOPY_KERNEL
>> STACKLEAK_ERASING OK: the rest of the thread stack is properly erased
>> -CFI_FORWARD_PROTO
>> +#CFI_FORWARD_PROTO
>> FORTIFIED_STRSCPY
>> FORTIFIED_OBJECT
>> FORTIFIED_SUBOBJECT

2022-03-09 20:48:43

by Kees Cook

[permalink] [raw]
Subject: Re: [PATCH 1/2] selftests/lkdtm: add config and turn off CFI_FORWARD_PROTO

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

>
> Cc: Kees Cook <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
> Fixes: 46d1a0f03d66 ("selftests/lkdtm: Add tests for LKDTM targets")
> Signed-off-by: Muhammad Usama Anjum <[email protected]>
> ---
> tools/testing/selftests/lkdtm/config | 2 ++
> tools/testing/selftests/lkdtm/tests.txt | 2 +-
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/lkdtm/config b/tools/testing/selftests/lkdtm/config
> index 46f39ee762086..adc9fa60057c5 100644
> --- a/tools/testing/selftests/lkdtm/config
> +++ b/tools/testing/selftests/lkdtm/config
> @@ -2,8 +2,10 @@ CONFIG_LKDTM=y
> CONFIG_DEBUG_LIST=y
> CONFIG_SLAB_FREELIST_HARDENED=y
> CONFIG_FORTIFY_SOURCE=y
> +CONFIG_GCC_PLUGIN_STACKLEAK=y
> CONFIG_HARDENED_USERCOPY=y
> CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
> +CONFIG_INIT_ON_FREE_DEFAULT_ON=y
> CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
> CONFIG_UBSAN=y
> CONFIG_UBSAN_BOUNDS=y
> diff --git a/tools/testing/selftests/lkdtm/tests.txt b/tools/testing/selftests/lkdtm/tests.txt
> index 6b36b7f5dcf96..aa947b0ce1eeb 100644
> --- a/tools/testing/selftests/lkdtm/tests.txt
> +++ b/tools/testing/selftests/lkdtm/tests.txt
> @@ -72,7 +72,7 @@ USERCOPY_STACK_FRAME_FROM
> USERCOPY_STACK_BEYOND
> USERCOPY_KERNEL
> STACKLEAK_ERASING OK: the rest of the thread stack is properly erased
> -CFI_FORWARD_PROTO
> +#CFI_FORWARD_PROTO
> FORTIFIED_STRSCPY
> FORTIFIED_OBJECT
> FORTIFIED_SUBOBJECT
> --
> 2.30.2
>

--
Kees Cook

2022-03-10 01:32:27

by Kees Cook

[permalink] [raw]
Subject: Re: [PATCH 2/2] selftests/lkdtm: add config

On Fri, Feb 18, 2022 at 01:56:20AM +0500, Muhammad Usama Anjum wrote:
> Add config option which is needed for SLAB_LINEAR_OVERFLOW test. It
> needs KASAN enabled.

I'd prefer this use the SLAB_DEBUG options -- KASAN is very heavy.

-Kees

>
> Cc: Kees Cook <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
> Fixes: 9c4f6ebc3665 ("lkdtm/heap: Add vmalloc linear overflow test")
> Signed-off-by: Muhammad Usama Anjum <[email protected]>
> ---
> tools/testing/selftests/lkdtm/config | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/tools/testing/selftests/lkdtm/config b/tools/testing/selftests/lkdtm/config
> index adc9fa60057c5..4e8af0f712f74 100644
> --- a/tools/testing/selftests/lkdtm/config
> +++ b/tools/testing/selftests/lkdtm/config
> @@ -7,6 +7,7 @@ CONFIG_HARDENED_USERCOPY=y
> CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
> CONFIG_INIT_ON_FREE_DEFAULT_ON=y
> CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
> +CONFIG_KASAN=y
> CONFIG_UBSAN=y
> CONFIG_UBSAN_BOUNDS=y
> CONFIG_UBSAN_TRAP=y
> --
> 2.30.2
>

--
Kees Cook

2022-03-11 14:49:42

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH 2/2] selftests/lkdtm: add config

On 3/10/22 12:23 AM, Kees Cook wrote:
> On Fri, Feb 18, 2022 at 01:56:20AM +0500, Muhammad Usama Anjum wrote:
>> Add config option which is needed for SLAB_LINEAR_OVERFLOW test. It
>> needs KASAN enabled.
>
> I'd prefer this use the SLAB_DEBUG options -- KASAN is very heavy.
I'll test it out and update in the next patch version.

--
Muhammad Usama Anjum

2022-03-11 21:46:06

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH 1/2] selftests/lkdtm: add config and turn off CFI_FORWARD_PROTO

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

2022-03-16 11:52:58

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH 2/2] selftests/lkdtm: add config

On 3/10/22 10:22 PM, Muhammad Usama Anjum wrote:
> On 3/10/22 12:23 AM, Kees Cook wrote:
>> On Fri, Feb 18, 2022 at 01:56:20AM +0500, Muhammad Usama Anjum wrote:
>>> Add config option which is needed for SLAB_LINEAR_OVERFLOW test. It
>>> needs KASAN enabled.
>>
>> I'd prefer this use the SLAB_DEBUG options -- KASAN is very heavy.
> I'll test it out and update in the next patch version.
> I've tested by removing KASAN and adding the following config:
CONFIG_SLAB=y
CONFIG_DEBUG_SLAB=y

The result of SLAB_LINEAR_OVERFLOW test doesn't remain deterministic in
this config. The task never crashes and hence stack trace never appears.
When executed several times we get "Slab corruption" logs and after some
more tries whole kernel crashes. I've not used DEBUG_SLAB before and not
sure if this is the expected behavior. If we aren't sure, we can keep
KASAN turned on instead.

--
Muhammad Usama Anjum

2022-04-05 00:48:02

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH 2/2] selftests/lkdtm: add config

Hi Kees,

Any thoughts?

On 3/15/22 4:55 PM, Muhammad Usama Anjum wrote:
> On 3/10/22 10:22 PM, Muhammad Usama Anjum wrote:
>> On 3/10/22 12:23 AM, Kees Cook wrote:
>>> On Fri, Feb 18, 2022 at 01:56:20AM +0500, Muhammad Usama Anjum wrote:
>>>> Add config option which is needed for SLAB_LINEAR_OVERFLOW test. It
>>>> needs KASAN enabled.
>>>
>>> I'd prefer this use the SLAB_DEBUG options -- KASAN is very heavy.
>> I'll test it out and update in the next patch version.
>> I've tested by removing KASAN and adding the following config:
> CONFIG_SLAB=y
> CONFIG_DEBUG_SLAB=y
>
> The result of SLAB_LINEAR_OVERFLOW test doesn't remain deterministic in
> this config. The task never crashes and hence stack trace never appears.
> When executed several times we get "Slab corruption" logs and after some
> more tries whole kernel crashes. I've not used DEBUG_SLAB before and not
> sure if this is the expected behavior. If we aren't sure, we can keep
> KASAN turned on instead.
>

--
Muhammad Usama Anjum

2022-04-16 01:57:34

by Muhammad Usama Anjum

[permalink] [raw]
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

2022-04-17 01:08:25

by Kees Cook

[permalink] [raw]
Subject: Re: [PATCH 2/2] selftests/lkdtm: add config

On Mon, Apr 04, 2022 at 12:50:01PM +0500, Muhammad Usama Anjum wrote:
> Hi Kees,
>
> Any thoughts?
>
> On 3/15/22 4:55 PM, Muhammad Usama Anjum wrote:
> > On 3/10/22 10:22 PM, Muhammad Usama Anjum wrote:
> >> On 3/10/22 12:23 AM, Kees Cook wrote:
> >>> On Fri, Feb 18, 2022 at 01:56:20AM +0500, Muhammad Usama Anjum wrote:
> >>>> Add config option which is needed for SLAB_LINEAR_OVERFLOW test. It
> >>>> needs KASAN enabled.
> >>>
> >>> I'd prefer this use the SLAB_DEBUG options -- KASAN is very heavy.
> >> I'll test it out and update in the next patch version.
> >> I've tested by removing KASAN and adding the following config:
> > CONFIG_SLAB=y
> > CONFIG_DEBUG_SLAB=y

I recommend slub instead:

CONFIG_SLUB=y
CONFIG_SLUB_DEBUG=y

and one more, see below...

> >
> > The result of SLAB_LINEAR_OVERFLOW test doesn't remain deterministic in
> > this config. The task never crashes and hence stack trace never appears.
> > When executed several times we get "Slab corruption" logs and after some
> > more tries whole kernel crashes. I've not used DEBUG_SLAB before and not
> > sure if this is the expected behavior. If we aren't sure, we can keep
> > KASAN turned on instead.

I think you need to enable the actual kmem debugging with a boot param
("slub_debug=ZF"), or with CONFIG_SLUB_DEBUG_ON=y.

--
Kees Cook

2022-04-17 08:35:30

by Kees Cook

[permalink] [raw]
Subject: Re: [PATCH 1/2] selftests/lkdtm: add config and turn off CFI_FORWARD_PROTO

On Thu, Apr 14, 2022 at 04:31:42PM +0500, Muhammad Usama Anjum wrote:
> 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.

I don't like the idea of disabling the test because this means it won't
have any output in CI systems to examine at all. I'd much rather have
tests that are expecting to fail to report XFAIL from the kernel
instead. (See things like lkdtm_UNSET_SMEP.)

--
Kees Cook