[PATCH] KASAN: prohibit KASAN+STRUCTLEAK combination

[PATCH] KASAN: prohibit KASAN+STRUCTLEAK combination

[Dmitry Vyukov]

Currently STRUCTLEAK inserts initialization out of live scope of
variables from KASAN point of view. This leads to KASAN false
positive reports. Prohibit this combination for now.

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: linux-mm@kvack.org
Cc: kasan-dev@googlegroups.com
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Kees Cook <keescook@google.com>

---

This combination leads to periodic confusion
and pointless debugging:

https://marc.info/?l=linux-kernel&m=151991367323082
https://marc.info/?l=linux-kernel&m=151992229326243
https://lkml.org/lkml/2017/11/30/33
---
 arch/Kconfig | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig
index 8e0d665c8d53..983578c44cca 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -464,6 +464,10 @@ config GCC_PLUGIN_LATENT_ENTROPY
 config GCC_PLUGIN_STRUCTLEAK
 	bool "Force initialization of variables containing userspace addresses"
 	depends on GCC_PLUGINS
+	# Currently STRUCTLEAK inserts initialization out of live scope of
+	# variables from KASAN point of view. This leads to KASAN false
+	# positive reports. Prohibit this combination for now.
+	depends on !KASAN
 	help
 	  This plugin zero-initializes any structures containing a
 	  __user attribute. This can prevent some classes of information
-- 
2.17.0.484.g0c8726318c-goog

Re: [PATCH] KASAN: prohibit KASAN+STRUCTLEAK combination

[Andrey Ryabinin]

On 04/19/2018 12:48 PM, Dmitry Vyukov wrote:

> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -464,6 +464,10 @@ config GCC_PLUGIN_LATENT_ENTROPY
>  config GCC_PLUGIN_STRUCTLEAK
>  	bool "Force initialization of variables containing userspace addresses"
>  	depends on GCC_PLUGINS
> +	# Currently STRUCTLEAK inserts initialization out of live scope of
> +	# variables from KASAN point of view. This leads to KASAN false
> +	# positive reports. Prohibit this combination for now.
> +	depends on !KASAN
                    KASAN_EXTRA

Re: [PATCH] KASAN: prohibit KASAN+STRUCTLEAK combination

[Dmitry Vyukov]

On Thu, Apr 19, 2018 at 7:21 PM, Andrey Ryabinin
<aryabinin@virtuozzo.com> wrote:
>
>
> On 04/19/2018 12:48 PM, Dmitry Vyukov wrote:
>
>> --- a/arch/Kconfig
>> +++ b/arch/Kconfig
>> @@ -464,6 +464,10 @@ config GCC_PLUGIN_LATENT_ENTROPY
>>  config GCC_PLUGIN_STRUCTLEAK
>>       bool "Force initialization of variables containing userspace addresses"
>>       depends on GCC_PLUGINS
>> +     # Currently STRUCTLEAK inserts initialization out of live scope of
>> +     # variables from KASAN point of view. This leads to KASAN false
>> +     # positive reports. Prohibit this combination for now.
>> +     depends on !KASAN
>                     KASAN_EXTRA

Remailed, thanks.