some problems about kasan

[zhong jiang <zhongjiang@huawei.com>]

1、 I feel confused about one of the cases when  testing the cases  kasan can solve . the function come from the kernel in the /lib/test_kasan.c.

  static noinline void __init kmalloc_uaf2(void)
{
	char *ptr1, *ptr2;
	size_t size = 43;

	pr_info("use-after-free after another kmalloc\n");
	ptr1 = kmalloc(size, GFP_KERNEL);
	if (!ptr1) {
		pr_err("Allocation failed\n");
		return;
	}

	kfree(ptr1);
	ptr2 = kmalloc(size, GFP_KERNEL);
	if (!ptr2) {
		pr_err("Allocation failed\n");
		return;
	}

	ptr1[40] = 'x';
	kfree(ptr2);
}

In the above function, the point ptr1 are probably  the same as the ptr2 . so the error not certain to occur.

2、Is the stack local variable out of bound access set by the GCC  ? I don't see any operate in the kernel

3、I want to know that the global variable size include redzone is allocated by the module_alloc().