[PATCH v5 3/5] lib/test_kasan: Add test for double-kzfree detection

[Marco Elver <elver@google.com>]

Adds a simple test that checks if double-kzfree is being detected
correctly.

Signed-off-by: Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: kasan-dev@googlegroups.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
---
 lib/test_kasan.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index e3c593c38eff..dda5da9f5bd4 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -619,6 +619,22 @@ static noinline void __init kasan_strings(void)
 	strnlen(ptr, 1);
 }
 
+static noinline void __init kmalloc_double_kzfree(void)
+{
+	char *ptr;
+	size_t size = 16;
+
+	pr_info("double-free (kzfree)\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	kzfree(ptr);
+	kzfree(ptr);
+}
+
 static int __init kmalloc_tests_init(void)
 {
 	/*
@@ -660,6 +676,7 @@ static int __init kmalloc_tests_init(void)
 	kasan_memchr();
 	kasan_memcmp();
 	kasan_strings();
+	kmalloc_double_kzfree();
 
 	kasan_restore_multi_shot(multishot);
 
-- 
2.22.0.410.gd8fdbe21b5-goog