linux-kernel - Re: [PATCH] kasan: disable kasan_strings() kunit test when CONFIG_FORTIFY

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Message-ID: <20250731110823-9224fbee-6d66-4029-9e92-19447cbcda64@linutronix.de>
Date: Thu, 31 Jul 2025 11:09:08 +0200
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Yeoreum Yun <yeoreum.yun@....com>
Cc: ryabinin.a.a@...il.com, glider@...gle.com, andreyknvl@...il.com, 
	dvyukov@...gle.com, vincenzo.frascino@....com, akpm@...ux-foundation.org, 
	kasan-dev@...glegroups.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kasan: disable kasan_strings() kunit test when
 CONFIG_FORTIFY_SOURCE enabled

On Thu, Jul 31, 2025 at 10:02:46AM +0100, Yeoreum Yun wrote:
> When CONFIG_FORTIFY_SOURCE is enabled, invalid access from source
> triggers __fortify_panic() which kills running task.
> 
> This makes failured of kasan_strings() kunit testcase since the
> kunit-try-cacth kthread running kasan_string() dies before checking the
> fault.
> 
> To address this, skip kasan_strings() kunit test when
> CONFIG_FORTIFY_SOURCE is enabled.
> 
> Signed-off-by: Yeoreum Yun <yeoreum.yun@....com>
> ---
>  mm/kasan/kasan_test_c.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c
> index 5f922dd38ffa..1577d3edabb4 100644
> --- a/mm/kasan/kasan_test_c.c
> +++ b/mm/kasan/kasan_test_c.c
> @@ -1576,6 +1576,12 @@ static void kasan_strings(struct kunit *test)
>  	 */
>  	KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_AMD_MEM_ENCRYPT);
> 
> +	/*
> +	 * Harden common str/mem functions kills the kunit-try-catch thread
> +	 * before checking the fault.
> +	 */
> +	KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_FORTIFY_SOURCE);

Would it be enough to enable -D__NO_FORTIFY for the whole of kasan_test_c.c?

> +
>  	ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO);
>  	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
> 
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
>