Re: [PATCH 03/32] flex_array: Add Kunit tests

David Gow
2022-05-04T03:01:06Z

On Wed, May 4, 2022 at 9:47 AM Kees Cook <keescook@chromium.org> wrote:
>
> Add tests for the new flexible array structure helpers. These can be run
> with:
>
> make ARCH=um mrproper
> ./tools/testing/kunit/kunit.py config

Nit: it shouldn't be necessary to run kunit.py config separately:
kunit.py run will configure the kernel if necessary.

> ./tools/testing/kunit/kunit.py run flex_array
>
> Cc: David Gow <davidgow@google.com>
> Cc: kunit-dev@googlegroups.com
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---

This looks pretty good to me: it certainly worked on the different
setups I tried (um, x86_64, x86_64+KASAN).

A few minor nitpicks inline, mostly around minor config-y things, or
things which weren't totally clear on my first read-through.

Hopefully one day, with the various stubbing features or something
similar, we'll be able to check against allocation failures in
flex_dup(), too, but otherwise nothing seems too obviously missing.

Reviewed-by: David Gow <davidgow@google.com>

-- David

> lib/Kconfig.debug | 12 +-
> lib/Makefile | 1 +
> lib/flex_array_kunit.c | 523 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 531 insertions(+), 5 deletions(-)
> create mode 100644 lib/flex_array_kunit.c
>
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 9077bb38bc93..8bae6b169c50 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -2551,11 +2551,6 @@ config OVERFLOW_KUNIT_TEST
> Builds unit tests for the check_*_overflow(), size_*(), allocation, and
> related functions.
>
> - For more information on KUnit and unit tests in general please refer
> - to the KUnit documentation in Documentation/dev-tools/kunit/.
> -
> - If unsure, say N.
> -

Nit: while I'm not against removing some of this boilerplate, is it
better suited for a separate commit?

> config STACKINIT_KUNIT_TEST
> tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
> depends on KUNIT
> @@ -2567,6 +2562,13 @@ config STACKINIT_KUNIT_TEST
> CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
> or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
>
> +config FLEX_ARRAY_KUNIT_TEST
> + tristate "Test flex_*() family of helper functions at runtime" if !KUNIT_ALL_TESTS
> + depends on KUNIT
> + default KUNIT_ALL_TESTS
> + help
> + Builds unit tests for flexible array copy helper functions.
> +

Nit: checkpatch warns that the description here may be insufficient:
WARNING: please write a help paragraph that fully describes the config symbol

> config TEST_UDELAY
> tristate "udelay test driver"
> help
> diff --git a/lib/Makefile b/lib/Makefile
> index 6b9ffc1bd1ee..9884318db330 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -366,6 +366,7 @@ obj-$(CONFIG_MEMCPY_KUNIT_TEST) += memcpy_kunit.o
> obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o
> CFLAGS_stackinit_kunit.o += $(call cc-disable-warning, switch-unreachable)
> obj-$(CONFIG_STACKINIT_KUNIT_TEST) += stackinit_kunit.o
> +obj-$(CONFIG_FLEX_ARRAY_KUNIT_TEST) += flex_array_kunit.o
>
> obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
>
> diff --git a/lib/flex_array_kunit.c b/lib/flex_array_kunit.c
> new file mode 100644
> index 000000000000..48bee88945b4
> --- /dev/null
> +++ b/lib/flex_array_kunit.c
> @@ -0,0 +1,523 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Test cases for flex_*() array manipulation helpers.
> + */
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <kunit/test.h>
> +#include <linux/device.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/flex_array.h>
> +
> +#define COMPARE_STRUCTS(STRUCT_A, STRUCT_B) do { \
> + STRUCT_A *ptr_A; \
> + STRUCT_B *ptr_B; \
> + int rc; \
> + size_t size_A, size_B; \
> + \
> + /* matching types for flex array elements and count */ \
> + KUNIT_EXPECT_EQ(test, sizeof(*ptr_A), sizeof(*ptr_B)); \
> + KUNIT_EXPECT_TRUE(test, __same_type(*ptr_A->data, \
> + *ptr_B->__flex_array_elements)); \
> + KUNIT_EXPECT_TRUE(test, __same_type(ptr_A->datalen, \
> + ptr_B->__flex_array_elements_count)); \
> + KUNIT_EXPECT_EQ(test, sizeof(*ptr_A->data), \
> + sizeof(*ptr_B->__flex_array_elements)); \
> + KUNIT_EXPECT_EQ(test, offsetof(typeof(*ptr_A), data), \
> + offsetof(typeof(*ptr_B), \
> + __flex_array_elements)); \
> + KUNIT_EXPECT_EQ(test, offsetof(typeof(*ptr_A), datalen), \
> + offsetof(typeof(*ptr_B), \
> + __flex_array_elements_count)); \
> + \
> + /* struct_size() vs __fas_bytes() */ \
> + size_A = struct_size(ptr_A, data, 13); \
> + rc = __fas_bytes(ptr_B, __flex_array_elements, \
> + __flex_array_elements_count, 13, &size_B); \
> + KUNIT_EXPECT_EQ(test, rc, 0); \
> + KUNIT_EXPECT_EQ(test, size_A, size_B); \
> + \
> + /* flex_array_size() vs __fas_elements_bytes() */ \
> + size_A = flex_array_size(ptr_A, data, 13); \
> + rc = __fas_elements_bytes(ptr_B, __flex_array_elements, \
> + __flex_array_elements_count, 13, &size_B); \
> + KUNIT_EXPECT_EQ(test, rc, 0); \
> + KUNIT_EXPECT_EQ(test, size_A, size_B); \
> + \
> + KUNIT_EXPECT_EQ(test, sizeof(*ptr_A) + size_A, \
> + offsetof(typeof(*ptr_A), data) + \
> + (sizeof(*ptr_A->data) * 13)); \
> + KUNIT_EXPECT_EQ(test, sizeof(*ptr_B) + size_B, \
> + offsetof(typeof(*ptr_B), \
> + __flex_array_elements) + \
> + (sizeof(*ptr_B->__flex_array_elements) * \
> + 13)); \
> +} while (0)
> +
> +struct normal {
> + size_t datalen;
> + u32 data[];
> +};
> +
> +struct decl_normal {
> + DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(size_t, datalen);
> + DECLARE_FLEX_ARRAY_ELEMENTS(u32, data);
> +};
> +
> +struct aligned {
> + unsigned short datalen;
> + char data[] __aligned(__alignof__(u64));
> +};
> +
> +struct decl_aligned {
> + DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(unsigned short, datalen);
> + DECLARE_FLEX_ARRAY_ELEMENTS(char, data) __aligned(__alignof__(u64));
> +};
> +
> +static void struct_test(struct kunit *test)
> +{
> + COMPARE_STRUCTS(struct normal, struct decl_normal);
> + COMPARE_STRUCTS(struct aligned, struct decl_aligned);
> +}

If I understand it, the purpose of this is to ensure that structs both
with and without the flexible array declaration have the same memory
layout?

If so, any chance of a comment briefly stating that's the purpose (or
renaming this test struct_layout_test())?

Also, would it make sense to do the same with the struct with internal
padding below?
> +
> +/* Flexible array structure with internal padding. */
> +struct flex_cpy_obj {
> + DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(u8, count);
> + unsigned long empty;
> + char induce_padding;
> + /* padding ends up here */
> + unsigned long after_padding;
> + DECLARE_FLEX_ARRAY_ELEMENTS(u32, flex);
> +};
> +
> +/* Encapsulating flexible array structure. */
> +struct flex_dup_obj {
> + unsigned long flags;
> + int junk;
> + struct flex_cpy_obj fas;
> +};
> +
> +/* Flexible array struct of only bytes. */
> +struct tiny_flex {
> + DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(u8, count);
> + DECLARE_FLEX_ARRAY_ELEMENTS(u8, byte_array);
> +};
> +
> +#define CHECK_COPY(ptr) do { \
> + typeof(*(ptr)) *_cc_dst = (ptr); \
> + KUNIT_EXPECT_EQ(test, _cc_dst->induce_padding, 0); \
> + memcpy(&padding, &_cc_dst->induce_padding + sizeof(_cc_dst->induce_padding), \
> + sizeof(padding)); \
> + /* Padding should be zero too. */ \
> + KUNIT_EXPECT_EQ(test, padding, 0); \
> + KUNIT_EXPECT_EQ(test, src->count, _cc_dst->count); \
> + KUNIT_EXPECT_EQ(test, _cc_dst->count, TEST_TARGET); \
> + for (i = 0; i < _cc_dst->count - 1; i++) { \
> + /* 'A' is 0x41, and here repeated in a u32. */ \

Would it be simpler to just note that the magic value is 0x41, rather
than have it be the character 'A'?

> + KUNIT_EXPECT_EQ(test, _cc_dst->flex[i], 0x41414141); \
> + } \
> + /* Last item should be different. */ \
> + KUNIT_EXPECT_EQ(test, _cc_dst->flex[_cc_dst->count - 1], 0x14141414); \
> +} while (0)
> +
> +/* Test copying from one flexible array struct into another. */
> +static void flex_cpy_test(struct kunit *test)
> +{
> +#define TEST_BOUNDS 13
> +#define TEST_TARGET 12
> +#define TEST_SMALL 10
> + struct flex_cpy_obj *src, *dst;
> + unsigned long padding;
> + int i, rc;
> +
> + /* Prepare open-coded source. */
> + src = kzalloc(struct_size(src, flex, TEST_BOUNDS), GFP_KERNEL);
> + src->count = TEST_BOUNDS;
> + memset(src->flex, 'A', flex_array_size(src, flex, TEST_BOUNDS));

As above, it's possibly nicer to just state 0x41 here, rather than
'A', since all we're doing is checking against a hex value.

> + src->flex[src->count - 2] = 0x14141414;
> + src->flex[src->count - 1] = 0x24242424;
> +
> + /* Prepare open-coded destination, alloc only. */
> + dst = kzalloc(struct_size(src, flex, TEST_BOUNDS), GFP_KERNEL);
> + /* Pre-fill with 0xFE marker. */
> + memset(dst, 0xFE, struct_size(src, flex, TEST_BOUNDS));
> + /* Pretend we're 1 element smaller. */
> + dst->count = TEST_TARGET;
> +
> + /* Pretend to match the target destination size. */
> + src->count = TEST_TARGET;
> +
> + rc = flex_cpy(dst, src);
> + KUNIT_EXPECT_EQ(test, rc, 0);
> + CHECK_COPY(dst);
> + /* Item past last copied item is unchanged from initial memset. */
> + KUNIT_EXPECT_EQ(test, dst->flex[dst->count], 0xFEFEFEFE);
> +
> + /* Now trip overflow, and verify we didn't clobber beyond end. */
> + src->count = TEST_BOUNDS;
> + rc = flex_cpy(dst, src);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + /* Item past last copied item is unchanged from initial memset. */
> + KUNIT_EXPECT_EQ(test, dst->flex[dst->count], 0xFEFEFEFE);
> +
> + /* Reset destination contents. */
> + memset(dst, 0xFD, struct_size(src, flex, TEST_BOUNDS));
> + dst->count = TEST_TARGET;
> +
> + /* Copy less than max. */
> + src->count = TEST_SMALL;
> + rc = flex_cpy(dst, src);
> + KUNIT_EXPECT_EQ(test, rc, 0);
> + /* Verify count was adjusted. */
> + KUNIT_EXPECT_EQ(test, dst->count, TEST_SMALL);
> + /* Verify element beyond src size was wiped. */
> + KUNIT_EXPECT_EQ(test, dst->flex[TEST_SMALL], 0);
> + /* Verify element beyond original dst size was untouched. */
> + KUNIT_EXPECT_EQ(test, dst->flex[TEST_TARGET], 0xFDFDFDFD);
> +
> + kfree(dst);
> + kfree(src);
> +#undef TEST_BOUNDS
> +#undef TEST_TARGET
> +#undef TEST_SMALL
> +}
> +
> +static void flex_dup_test(struct kunit *test)
> +{
> +#define TEST_TARGET 12
> + struct flex_cpy_obj *src, *dst = NULL, **null = NULL;
> + struct flex_dup_obj *encap = NULL;
> + unsigned long padding;
> + int i, rc;
> +
> + /* Prepare open-coded source. */
> + src = kzalloc(struct_size(src, flex, TEST_TARGET), GFP_KERNEL);
> + src->count = TEST_TARGET;
> + memset(src->flex, 'A', flex_array_size(src, flex, TEST_TARGET));
> + src->flex[src->count - 1] = 0x14141414;
> +
> + /* Reject NULL @alloc. */
> + rc = flex_dup(null, src, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -EINVAL);
> +
> + /* Check good copy. */
> + rc = flex_dup(&dst, src, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, 0);
> + KUNIT_ASSERT_TRUE(test, dst != NULL);
> + CHECK_COPY(dst);
> +
> + /* Reject non-NULL *@alloc. */
> + rc = flex_dup(&dst, src, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -EINVAL);
> +
> + kfree(dst);
> +
> + /* Check good encap copy. */
> + rc = __flex_dup(&encap, .fas, src, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, 0);
> + KUNIT_ASSERT_TRUE(test, dst != NULL);
> + CHECK_COPY(&encap->fas);
> + /* Check that items external to "fas" are zero. */
> + KUNIT_EXPECT_EQ(test, encap->flags, 0);
> + KUNIT_EXPECT_EQ(test, encap->junk, 0);
> + kfree(encap);
> +#undef MAGIC_WORD

MAGIC_WORD isn't defined (or used) for flux_dup_test? Is it worth
using it (or something similar) for the 'A' / 0x14141414 and the
CHECK_COPY() macro?

> +#undef TEST_TARGET
> +}
> +
> +static void mem_to_flex_test(struct kunit *test)
> +{
> +#define TEST_TARGET 9
> +#define TEST_MAX U8_MAX
> +#define MAGIC_WORD 0x03030303
> + u8 magic_byte = MAGIC_WORD & 0xff;
> + struct flex_cpy_obj *dst;
> + size_t big = (size_t)INT_MAX + 1;
> + char small[] = "Hello";
> + char *src;
> + u32 src_len;
> + int rc;
> +
> + /* Open coded allocations, 1 larger than actually used. */
> + src_len = flex_array_size(dst, flex, TEST_MAX + 1);
> + src = kzalloc(src_len, GFP_KERNEL);
> + dst = kzalloc(struct_size(dst, flex, TEST_MAX + 1), GFP_KERNEL);
> + dst->count = TEST_TARGET;
> +
> + /* Fill source. */
> + memset(src, magic_byte, src_len);
> +
> + /* Short copy is fine. */
> + KUNIT_EXPECT_EQ(test, dst->flex[0], 0);
> + KUNIT_EXPECT_EQ(test, dst->flex[1], 0);
> + rc = mem_to_flex(dst, src, 1);
> + KUNIT_EXPECT_EQ(test, rc, 0);
> + KUNIT_EXPECT_EQ(test, dst->count, 1);
> + KUNIT_EXPECT_EQ(test, dst->after_padding, 0);
> + KUNIT_EXPECT_EQ(test, dst->flex[0], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, dst->flex[1], 0);
> + dst->count = TEST_TARGET;
> +
> + /* Reject negative elements count. */
> + rc = mem_to_flex(dst, small, -1);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + /* Make sure dst is unchanged. */
> + KUNIT_EXPECT_EQ(test, dst->flex[0], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, dst->flex[1], 0);
> +
> + /* Reject compile-time read overflow. */
> + rc = mem_to_flex(dst, small, 20);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + /* Make sure dst is unchanged. */
> + KUNIT_EXPECT_EQ(test, dst->flex[0], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, dst->flex[1], 0);
> +
> + /* Reject giant buffer source. */
> + rc = mem_to_flex(dst, small, big);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + /* Make sure dst is unchanged. */
> + KUNIT_EXPECT_EQ(test, dst->flex[0], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, dst->flex[1], 0);
> +
> + /* Copy beyond storage size is rejected. */
> + dst->count = TEST_MAX;
> + KUNIT_EXPECT_EQ(test, dst->flex[TEST_MAX - 1], 0);
> + KUNIT_EXPECT_EQ(test, dst->flex[TEST_MAX], 0);
> + rc = mem_to_flex(dst, src, TEST_MAX + 1);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + /* Make sure dst is unchanged. */
> + KUNIT_EXPECT_EQ(test, dst->flex[0], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, dst->flex[1], 0);
> +
> + kfree(dst);
> + kfree(src);
> +#undef MAGIC_WORD
> +#undef TEST_MAX
> +#undef TEST_TARGET
> +}
> +
> +static void mem_to_flex_dup_test(struct kunit *test)
> +{
> +#define ELEMENTS_COUNT 259
> +#define MAGIC_WORD 0xABABABAB
> + u8 magic_byte = MAGIC_WORD & 0xff;
> + struct flex_dup_obj *obj = NULL;
> + struct tiny_flex *tiny = NULL, **null = NULL;
> + size_t src_len, count, big = (size_t)INT_MAX + 1;
> + char small[] = "Hello";
> + u8 *src;
> + int rc;
> +
> + src_len = struct_size(tiny, byte_array, ELEMENTS_COUNT);
> + src = kzalloc(src_len, GFP_KERNEL);
> + KUNIT_ASSERT_TRUE(test, src != NULL);
> + /* Fill with bytes. */
> + memset(src, magic_byte, src_len);
> + KUNIT_EXPECT_EQ(test, src[0], magic_byte);
> + KUNIT_EXPECT_EQ(test, src[src_len / 2], magic_byte);
> + KUNIT_EXPECT_EQ(test, src[src_len - 1], magic_byte);
> +
> + /* Reject storage exceeding elements_count type. */
> + count = ELEMENTS_COUNT;
> + rc = mem_to_flex_dup(&tiny, src, count, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + KUNIT_EXPECT_TRUE(test, tiny == NULL);
> +
> + /* Reject negative elements count. */
> + rc = mem_to_flex_dup(&tiny, src, -1, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + KUNIT_EXPECT_TRUE(test, tiny == NULL);
> +
> + /* Reject compile-time read overflow. */
> + rc = mem_to_flex_dup(&tiny, small, 20, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + KUNIT_EXPECT_TRUE(test, tiny == NULL);
> +
> + /* Reject giant buffer source. */
> + rc = mem_to_flex_dup(&tiny, small, big, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + KUNIT_EXPECT_TRUE(test, tiny == NULL);
> +
> + /* Reject NULL @alloc. */
> + rc = mem_to_flex_dup(null, src, count, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -EINVAL);
> +
> + /* Allow reasonable count.*/
> + count = ELEMENTS_COUNT / 2;
> + rc = mem_to_flex_dup(&tiny, src, count, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, 0);
> + KUNIT_ASSERT_TRUE(test, tiny != NULL);
> + /* Spot check the copy happened. */
> + KUNIT_EXPECT_EQ(test, tiny->count, count);
> + KUNIT_EXPECT_EQ(test, tiny->byte_array[0], magic_byte);
> + KUNIT_EXPECT_EQ(test, tiny->byte_array[count / 2], magic_byte);
> + KUNIT_EXPECT_EQ(test, tiny->byte_array[count - 1], magic_byte);
> +
> + /* Reject non-NULL *@alloc. */
> + rc = mem_to_flex_dup(&tiny, src, count, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -EINVAL);
> + kfree(tiny);
> +
> + /* Works with encapsulation too. */
> + count = ELEMENTS_COUNT / 10;
> + rc = __mem_to_flex_dup(&obj, .fas, src, count, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, 0);
> + KUNIT_ASSERT_TRUE(test, obj != NULL);
> + /* Spot check the copy happened. */
> + KUNIT_EXPECT_EQ(test, obj->fas.count, count);
> + KUNIT_EXPECT_EQ(test, obj->fas.after_padding, 0);
> + KUNIT_EXPECT_EQ(test, obj->fas.flex[0], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, obj->fas.flex[count / 2], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, obj->fas.flex[count - 1], MAGIC_WORD);
> + /* Check members before flexible array struct are zero. */
> + KUNIT_EXPECT_EQ(test, obj->flags, 0);
> + KUNIT_EXPECT_EQ(test, obj->junk, 0);
> + kfree(obj);
> +#undef MAGIC_WORD
> +#undef ELEMENTS_COUNT
> +}
> +
> +static void flex_to_mem_test(struct kunit *test)
> +{
> +#define ELEMENTS_COUNT 200
> +#define MAGIC_WORD 0xF1F2F3F4
> + struct flex_cpy_obj *src;
> + typeof(*src->flex) *cast;
> + size_t src_len = struct_size(src, flex, ELEMENTS_COUNT);
> + size_t copy_len = flex_array_size(src, flex, ELEMENTS_COUNT);
> + int i, rc;
> + size_t bytes = 0;
> + u8 too_small;
> + u8 *dst;
> +
> + /* Create a filled flexible array struct. */
> + src = kzalloc(src_len, GFP_KERNEL);
> + KUNIT_ASSERT_TRUE(test, src != NULL);
> + src->count = ELEMENTS_COUNT;
> + src->after_padding = 13;
> + for (i = 0; i < ELEMENTS_COUNT; i++)
> + src->flex[i] = MAGIC_WORD;
> +
> + /* Over-allocate space to do past-src_len checking. */
> + dst = kzalloc(src_len * 2, GFP_KERNEL);
> + KUNIT_ASSERT_TRUE(test, dst != NULL);
> + cast = (void *)dst;
> +
> + /* Fail if dst is too small. */
> + rc = flex_to_mem(dst, copy_len - 1, src, &bytes);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + /* Make sure nothing was copied. */
> + KUNIT_EXPECT_EQ(test, bytes, 0);
> + KUNIT_EXPECT_EQ(test, cast[0], 0);
> +
> + /* Fail if type too small to hold size of copy. */
> + KUNIT_EXPECT_GT(test, copy_len, type_max(typeof(too_small)));
> + rc = flex_to_mem(dst, copy_len, src, &too_small);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + /* Make sure nothing was copied. */
> + KUNIT_EXPECT_EQ(test, bytes, 0);
> + KUNIT_EXPECT_EQ(test, cast[0], 0);
> +
> + /* Check good copy. */
> + rc = flex_to_mem(dst, copy_len, src, &bytes);
> + KUNIT_EXPECT_EQ(test, rc, 0);
> + KUNIT_EXPECT_EQ(test, bytes, copy_len);
> + /* Spot check the copy */
> + KUNIT_EXPECT_EQ(test, cast[0], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, cast[ELEMENTS_COUNT / 2], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, cast[ELEMENTS_COUNT - 1], MAGIC_WORD);
> + /* Make sure nothing was written after last element. */
> + KUNIT_EXPECT_EQ(test, cast[ELEMENTS_COUNT], 0);
> +
> + kfree(dst);
> + kfree(src);
> +#undef MAGIC_WORD
> +#undef ELEMENTS_COUNT
> +}
> +
> +static void flex_to_mem_dup_test(struct kunit *test)
> +{
> +#define ELEMENTS_COUNT 210
> +#define MAGIC_WORD 0xF0F1F2F3
> + struct flex_dup_obj *obj, **null = NULL;
> + struct flex_cpy_obj *src;
> + typeof(*src->flex) *cast;
> + size_t obj_len = struct_size(obj, fas.flex, ELEMENTS_COUNT);
> + size_t src_len = struct_size(src, flex, ELEMENTS_COUNT);
> + size_t copy_len = flex_array_size(src, flex, ELEMENTS_COUNT);
> + int i, rc;
> + size_t bytes = 0;
> + u8 too_small = 0;
> + u8 *dst = NULL;
> +
> + /* Create a filled flexible array struct. */
> + obj = kzalloc(obj_len, GFP_KERNEL);
> + KUNIT_ASSERT_TRUE(test, obj != NULL);
> + obj->fas.count = ELEMENTS_COUNT;
> + obj->fas.after_padding = 13;
> + for (i = 0; i < ELEMENTS_COUNT; i++)
> + obj->fas.flex[i] = MAGIC_WORD;
> + src = &obj->fas;
> +
> + /* Fail if type too small to hold size of copy. */
> + KUNIT_EXPECT_GT(test, src_len, type_max(typeof(too_small)));
> + rc = flex_to_mem_dup(&dst, &too_small, src, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -E2BIG);
> + KUNIT_EXPECT_TRUE(test, dst == NULL);
> + KUNIT_EXPECT_EQ(test, too_small, 0);
> +
> + /* Fail if @alloc_size is NULL. */
> + KUNIT_EXPECT_TRUE(test, dst == NULL);
> + rc = flex_to_mem_dup(&dst, dst, src, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -EINVAL);
> + KUNIT_EXPECT_TRUE(test, dst == NULL);
> +
> + /* Fail if @alloc is NULL. */
> + rc = flex_to_mem_dup(null, &bytes, src, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -EINVAL);
> + KUNIT_EXPECT_TRUE(test, dst == NULL);
> + KUNIT_EXPECT_EQ(test, bytes, 0);
> +
> + /* Check good copy. */
> + rc = flex_to_mem_dup(&dst, &bytes, src, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, 0);
> + KUNIT_EXPECT_TRUE(test, dst != NULL);
> + KUNIT_EXPECT_EQ(test, bytes, copy_len);
> + cast = (void *)dst;
> + /* Spot check the copy */
> + KUNIT_EXPECT_EQ(test, cast[0], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, cast[ELEMENTS_COUNT / 2], MAGIC_WORD);
> + KUNIT_EXPECT_EQ(test, cast[ELEMENTS_COUNT - 1], MAGIC_WORD);
> +
> + /* Fail if *@alloc is non-NULL. */
> + bytes = 0;
> + rc = flex_to_mem_dup(&dst, &bytes, src, GFP_KERNEL);
> + KUNIT_EXPECT_EQ(test, rc, -EINVAL);
> + KUNIT_EXPECT_EQ(test, bytes, 0);
> +
> + kfree(dst);
> + kfree(obj);
> +#undef MAGIC_WORD
> +#undef ELEMENTS_COUNT
> +}
> +
> +static struct kunit_case flex_array_test_cases[] = {
> + KUNIT_CASE(struct_test),
> + KUNIT_CASE(flex_cpy_test),
> + KUNIT_CASE(flex_dup_test),
> + KUNIT_CASE(mem_to_flex_test),
> + KUNIT_CASE(mem_to_flex_dup_test),
> + KUNIT_CASE(flex_to_mem_test),
> + KUNIT_CASE(flex_to_mem_dup_test),
> + {}
> +};
> +
> +static struct kunit_suite flex_array_test_suite = {
> + .name = "flex_array",
> + .test_cases = flex_array_test_cases,
> +};
> +
> +kunit_test_suite(flex_array_test_suite);
> +
> +MODULE_LICENSE("GPL");
> --
> 2.32.0
>