kasan: test: only do kmalloc_uaf_memset for generic mode

kmalloc_uaf_memset() writes to freed memory, which is only safe with the
GENERIC mode (as it uses quarantine).  For other modes, this test corrupts
kernel memory, which might result in a crash.

Only enable kmalloc_uaf_memset() for the GENERIC mode.

Link: https://lkml.kernel.org/r/2e1c87b607b1292556cde3cab2764f108542b60c.1628779805.git.andreyknvl@gmail.comSigned-off-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/test_kasan.c

@@ -534,6 +534,12 @@ static void kmalloc_uaf_memset(struct kunit *test)
 	char *ptr;
 	size_t size = 33;
 
+	/*
+	 * Only generic KASAN uses quarantine, which is required to avoid a
+	 * kernel memory corruption this test causes.
+	 */
+	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC);
+
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);