linux-kernel - Re: [RFC 3/3] lib: Convert test_user

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Date:   Wed, 15 Jul 2020 19:34:06 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Vitor Massaru Iha <vitor@...saru.org>
Cc:     kunit-dev@...glegroups.com, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org, brendanhiggins@...gle.com,
        davidgow@...gle.com, skhan@...uxfoundation.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [RFC 3/3] lib: Convert test_user_copy to KUnit test

On Wed, Jul 15, 2020 at 12:11:20AM -0300, Vitor Massaru Iha wrote:
> This adds the conversion of the runtime tests of test_user_copy fuctions,
> from `lib/test_user_copy.c`to KUnit tests.
> 
> Signed-off-by: Vitor Massaru Iha <vitor@...saru.org>
> [...]
> @@ -16,6 +16,7 @@
>  #include <linux/slab.h>
>  #include <linux/uaccess.h>
>  #include <linux/vmalloc.h>
> +#include <kunit/test.h>
>  
>  /*
>   * Several 32-bit architectures support 64-bit {get,put}_user() calls.
> @@ -31,26 +32,16 @@
>  # define TEST_U64
>  #endif
>  
> -#define test(condition, msg, ...)					\
> -({									\
> -	int cond = (condition);						\
> -	if (cond)							\
> -		pr_warn("[%d] " msg "\n", __LINE__, ##__VA_ARGS__);	\
> -	cond;								\
> -})
> -
>  static bool is_zeroed(void *from, size_t size)
>  {
>  	return memchr_inv(from, 0x0, size) == NULL;
>  }
>  
> -static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size)
> +static void test_check_nonzero_user(struct kunit *test, char *kmem, char __user *umem, size_t size)
>  {
> -	int ret = 0;
>  	size_t start, end, i, zero_start, zero_end;
>  
> -	if (test(size < 2 * PAGE_SIZE, "buffer too small"))
> -		return -EINVAL;
> +	KUNIT_EXPECT_FALSE_MSG(test, size < 2 * PAGE_SIZE, "buffer too small");

I think this could be a much smaller diff if you just replaced the
"test" macro:

#define test(condition, msg, ...)					\
({									\
	int cond = !!(condition);					\
	KUNIT_EXPECT_FALSE_MSG(kunit_context, cond, msg, ##__VA_ARGS__);\
	cond;								\
})

-- 
Kees Cook