Merge tag 'overflow-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull overflow updates from Kees Cook:
 "These changes come in roughly two halves: support of Gustavo A. R.
  Silva's struct_size() work via additional helpers for catching
  overflow allocation size calculations, and conversions of selftests to
  KUnit (which includes some tweaks for UML + Clang):

   - Convert overflow selftest to KUnit

   - Convert stackinit selftest to KUnit

   - Implement size_t saturating arithmetic helpers

   - Allow struct_size() to be used in initializers"

* tag 'overflow-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  lib: stackinit: Convert to KUnit
  um: Allow builds with Clang
  lib: overflow: Convert to Kunit
  overflow: Provide constant expression struct_size
  overflow: Implement size_t saturating arithmetic helpers
  test_overflow: Regularize test reporting output

9 files changed, 518 insertions, 458 deletions

diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index 388cb19f5dbb..a6e36d9c3d14 100644
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -71,6 +71,9 @@ Instead, the 2-factor form of the allocator should be used::
 
 	foo = kmalloc_array(count, size, GFP_KERNEL);
 
+Specifically, kmalloc() can be replaced with kmalloc_array(), and
+kzalloc() can be replaced with kcalloc().
+
 If no 2-factor form is available, the saturate-on-overflow helpers should
 be used::
 
@@ -91,9 +94,20 @@ Instead, use the helper::
         array usage and switch to a `flexible array member
         <#zero-length-and-one-element-arrays>`_ instead.
 
-See array_size(), array3_size(), and struct_size(),
-for more details as well as the related check_add_overflow() and
-check_mul_overflow() family of functions.
+For other calculations, please compose the use of the size_mul(),
+size_add(), and size_sub() helpers. For example, in the case of::
+
+	foo = krealloc(current_size + chunk_size * (count - 3), GFP_KERNEL);
+
+Instead, use the helpers::
+
+	foo = krealloc(size_add(current_size,
+				size_mul(chunk_size,
+					 size_sub(count, 3))), GFP_KERNEL);
+
+For more details, also see array3_size() and flex_array_size(),
+as well as the related check_mul_overflow(), check_add_overflow(),
+check_sub_overflow(), and check_shl_overflow() family of functions.
 
 simple_strtol(), simple_strtoll(), simple_strtoul(), simple_strtoull()
 ----------------------------------------------------------------------
diff --git a/arch/um/os-Linux/execvp.c b/arch/um/os-Linux/execvp.c
index 84a0777c2a45..c09a5fd5e225 100644
--- a/arch/um/os-Linux/execvp.c
+++ b/arch/um/os-Linux/execvp.c
@@ -93,6 +93,7 @@ int execvp_noalloc(char *buf, const char *file, char *const argv[])
 					   up finding no executable we can use, we want to diagnose
 					   that we did find one but were denied access.  */
 					got_eacces = 1;
+					break;
 				case ENOENT:
 				case ESTALE:
 				case ENOTDIR:
diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index bae61554abcc..e54a9814ccf1 100644
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -8,12 +8,11 @@
 #define __FRAME_OFFSETS
 #include <linux/ptrace.h>
 #include <asm/types.h>
+#include <linux/kbuild.h>
 
-#define DEFINE(sym, val) \
-	asm volatile("\n->" #sym " %0 " #val : : "i" (val))
-
-#define DEFINE_LONGS(sym, val) \
-	asm volatile("\n->" #sym " %0 " #val : : "i" (val/sizeof(unsigned long)))
+#define DEFINE_LONGS(sym, val)	\
+	COMMENT(#val " / sizeof(unsigned long)");	\
+	DEFINE(sym, val / sizeof(unsigned long))
 
 void foo(void)
 {
diff --git a/include/linux/overflow.h b/include/linux/overflow.h
index 4669632bd72b..f1221d11f8e5 100644
--- a/include/linux/overflow.h
+++ b/include/linux/overflow.h
@@ -4,6 +4,7 @@
 
 #include <linux/compiler.h>
 #include <linux/limits.h>
+#include <linux/const.h>
 
 /*
  * We need to compute the minimum and maximum values representable in a given
@@ -118,81 +119,94 @@ static inline bool __must_check __must_check_overflow(bool overflow)
 }))
 
 /**
- * array_size() - Calculate size of 2-dimensional array.
- *
- * @a: dimension one
- * @b: dimension two
+ * size_mul() - Calculate size_t multiplication with saturation at SIZE_MAX
  *
- * Calculates size of 2-dimensional array: @a * @b.
+ * @factor1: first factor
+ * @factor2: second factor
  *
- * Returns: number of bytes needed to represent the array or SIZE_MAX on
- * overflow.
+ * Returns: calculate @factor1 * @factor2, both promoted to size_t,
+ * with any overflow causing the return value to be SIZE_MAX. The
+ * lvalue must be size_t to avoid implicit type conversion.
  */
-static inline __must_check size_t array_size(size_t a, size_t b)
+static inline size_t __must_check size_mul(size_t factor1, size_t factor2)
 {
 	size_t bytes;
 
-	if (check_mul_overflow(a, b, &bytes))
+	if (check_mul_overflow(factor1, factor2, &bytes))
 		return SIZE_MAX;
 
 	return bytes;
 }
 
 /**
- * array3_size() - Calculate size of 3-dimensional array.
+ * size_add() - Calculate size_t addition with saturation at SIZE_MAX
  *
- * @a: dimension one
- * @b: dimension two
- * @c: dimension three
- *
- * Calculates size of 3-dimensional array: @a * @b * @c.
+ * @addend1: first addend
+ * @addend2: second addend
  *
- * Returns: number of bytes needed to represent the array or SIZE_MAX on
- * overflow.
+ * Returns: calculate @addend1 + @addend2, both promoted to size_t,
+ * with any overflow causing the return value to be SIZE_MAX. The
+ * lvalue must be size_t to avoid implicit type conversion.
  */
-static inline __must_check size_t array3_size(size_t a, size_t b, size_t c)
+static inline size_t __must_check size_add(size_t addend1, size_t addend2)
 {
 	size_t bytes;
 
-	if (check_mul_overflow(a, b, &bytes))
-		return SIZE_MAX;
-	if (check_mul_overflow(bytes, c, &bytes))
+	if (check_add_overflow(addend1, addend2, &bytes))
 		return SIZE_MAX;
 
 	return bytes;
 }
 
-/*
- * Compute a*b+c, returning SIZE_MAX on overflow. Internal helper for
- * struct_size() below.
+/**
+ * size_sub() - Calculate size_t subtraction with saturation at SIZE_MAX
+ *
+ * @minuend: value to subtract from
+ * @subtrahend: value to subtract from @minuend
+ *
+ * Returns: calculate @minuend - @subtrahend, both promoted to size_t,
+ * with any overflow causing the return value to be SIZE_MAX. For
+ * composition with the size_add() and size_mul() helpers, neither
+ * argument may be SIZE_MAX (or the result with be forced to SIZE_MAX).
+ * The lvalue must be size_t to avoid implicit type conversion.
  */
-static inline __must_check size_t __ab_c_size(size_t a, size_t b, size_t c)
+static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
 {
 	size_t bytes;
 
-	if (check_mul_overflow(a, b, &bytes))
-		return SIZE_MAX;
-	if (check_add_overflow(bytes, c, &bytes))
+	if (minuend == SIZE_MAX || subtrahend == SIZE_MAX ||
+	    check_sub_overflow(minuend, subtrahend, &bytes))
 		return SIZE_MAX;
 
 	return bytes;
 }
 
 /**
- * struct_size() - Calculate size of structure with trailing array.
- * @p: Pointer to the structure.
- * @member: Name of the array member.
- * @count: Number of elements in the array.
+ * array_size() - Calculate size of 2-dimensional array.
  *
- * Calculates size of memory needed for structure @p followed by an
- * array of @count number of @member elements.
+ * @a: dimension one
+ * @b: dimension two
  *
- * Return: number of bytes needed or SIZE_MAX on overflow.
+ * Calculates size of 2-dimensional array: @a * @b.
+ *
+ * Returns: number of bytes needed to represent the array or SIZE_MAX on
+ * overflow.
  */
-#define struct_size(p, member, count)					\
-	__ab_c_size(count,						\
-		    sizeof(*(p)->member) + __must_be_array((p)->member),\
-		    sizeof(*(p)))
+#define array_size(a, b)	size_mul(a, b)
+
+/**
+ * array3_size() - Calculate size of 3-dimensional array.
+ *
+ * @a: dimension one
+ * @b: dimension two
+ * @c: dimension three
+ *
+ * Calculates size of 3-dimensional array: @a * @b * @c.
+ *
+ * Returns: number of bytes needed to represent the array or SIZE_MAX on
+ * overflow.
+ */
+#define array3_size(a, b, c)	size_mul(size_mul(a, b), c)
 
 /**
  * flex_array_size() - Calculate size of a flexible array member
@@ -208,7 +222,25 @@ static inline __must_check size_t __ab_c_size(size_t a, size_t b, size_t c)
  * Return: number of bytes needed or SIZE_MAX on overflow.
  */
 #define flex_array_size(p, member, count)				\
-	array_size(count,						\
-		    sizeof(*(p)->member) + __must_be_array((p)->member))
+	__builtin_choose_expr(__is_constexpr(count),			\
+		(count) * sizeof(*(p)->member) + __must_be_array((p)->member),	\
+		size_mul(count, sizeof(*(p)->member) + __must_be_array((p)->member)))
+
+/**
+ * struct_size() - Calculate size of structure with trailing flexible array.
+ *
+ * @p: Pointer to the structure.
+ * @member: Name of the array member.
+ * @count: Number of elements in the array.
+ *
+ * Calculates size of memory needed for structure @p followed by an
+ * array of @count number of @member elements.
+ *
+ * Return: number of bytes needed or SIZE_MAX on overflow.
+ */
+#define struct_size(p, member, count)					\
+	__builtin_choose_expr(__is_constexpr(count),			\
+		sizeof(*(p)) + flex_array_size(p, member, count),	\
+		size_add(sizeof(*(p)), flex_array_size(p, member, count)))
 
 #endif /* __LINUX_OVERFLOW_H */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 14b89aa37c5c..a5556ab05240 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2214,9 +2214,6 @@ config TEST_UUID
 config TEST_XARRAY
 	tristate "Test the XArray code at runtime"
 
-config TEST_OVERFLOW
-	tristate "Test check_*_overflow() functions at runtime"
-
 config TEST_RHASHTABLE
 	tristate "Perform selftest on resizable hash table"
 	help
@@ -2501,6 +2498,30 @@ config MEMCPY_KUNIT_TEST
 
 	  If unsure, say N.
 
+config OVERFLOW_KUNIT_TEST
+	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  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.
+
+config STACKINIT_KUNIT_TEST
+	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  Test if the kernel is zero-initializing stack variables and
+	  padding. Coverage is controlled by compiler flags,
+	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
+	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
+	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
+
 config TEST_UDELAY
 	tristate "udelay test driver"
 	help
@@ -2592,17 +2613,6 @@ config TEST_OBJAGG
 	  Enable this option to test object aggregation manager on boot
 	  (or module load).
 
-
-config TEST_STACKINIT
-	tristate "Test level of stack variable initialization"
-	help
-	  Test if the kernel is zero-initializing stack variables and
-	  padding. Coverage is controlled by compiler flags,
-	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
-	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
-
-	  If unsure, say N.
-
 config TEST_MEMINIT
 	tristate "Test heap/page initialization"
 	help
diff --git a/lib/Makefile b/lib/Makefile
index 300f569c626b..353bc09ce38d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -77,7 +77,6 @@ obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
 obj-$(CONFIG_TEST_MIN_HEAP) += test_min_heap.o
 obj-$(CONFIG_TEST_LKM) += test_module.o
 obj-$(CONFIG_TEST_VMALLOC) += test_vmalloc.o
-obj-$(CONFIG_TEST_OVERFLOW) += test_overflow.o
 obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
 obj-$(CONFIG_TEST_SORT) += test_sort.o
 obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
@@ -94,8 +93,6 @@ obj-$(CONFIG_TEST_KMOD) += test_kmod.o
 obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o
 obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o
 obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o
-CFLAGS_test_stackinit.o += $(call cc-disable-warning, switch-unreachable)
-obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o
 obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o
 obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o
 obj-$(CONFIG_TEST_LOCKUP) += test_lockup.o
@@ -363,6 +360,9 @@ obj-$(CONFIG_BITS_TEST) += test_bits.o
 obj-$(CONFIG_CMDLINE_KUNIT_TEST) += cmdline_kunit.o
 obj-$(CONFIG_SLUB_KUNIT_TEST) += slub_kunit.o
 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_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
 
diff --git a/lib/test_overflow.c b/lib/overflow_kunit.c
index 7a4b6f6c5473..475f0c064bf6 100644
--- a/lib/test_overflow.c
+++ b/lib/overflow_kunit.c
@@ -1,11 +1,13 @@
 // SPDX-License-Identifier: GPL-2.0 OR MIT
 /*
- * Test cases for arithmetic overflow checks.
+ * Test cases for arithmetic overflow checks. See:
+ * https://www.kernel.org/doc/html/latest/dev-tools/kunit/kunit-tool.html#configuring-building-and-running-tests
+ *	./tools/testing/kunit/kunit.py run overflow [--raw_output]
  */
 #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/mm.h>
 #include <linux/module.h>
@@ -19,7 +21,7 @@
 		t a, b;				\
 		t sum, diff, prod;		\
 		bool s_of, d_of, p_of;		\
-	} t ## _tests[] __initconst
+	} t ## _tests[]
 
 DEFINE_TEST_ARRAY(u8) = {
 	{0, 0, 0, 0, 0, false, false, false},
@@ -220,43 +222,31 @@ DEFINE_TEST_ARRAY(s64) = {
 	bool _of;						\
 								\
 	_of = check_ ## op ## _overflow(a, b, &_r);		\
-	if (_of != of) {					\
-		pr_warn("expected "fmt" "sym" "fmt		\
-			" to%s overflow (type %s)\n",		\
-			a, b, of ? "" : " not", #t);		\
-		err = 1;					\
-	}							\
-	if (_r != r) {						\
-		pr_warn("expected "fmt" "sym" "fmt" == "	\
-			fmt", got "fmt" (type %s)\n",		\
-			a, b, r, _r, #t);			\
-		err = 1;					\
-	}							\
+	KUNIT_EXPECT_EQ_MSG(test, _of, of,			\
+		"expected "fmt" "sym" "fmt" to%s overflow (type %s)\n",	\
+		a, b, of ? "" : " not", #t);			\
+	KUNIT_EXPECT_EQ_MSG(test, _r, r,			\
+		"expected "fmt" "sym" "fmt" == "fmt", got "fmt" (type %s)\n", \
+		a, b, r, _r, #t);				\
 } while (0)
 
 #define DEFINE_TEST_FUNC(t, fmt)					\
-static int __init do_test_ ## t(const struct test_ ## t *p)		\
+static void do_test_ ## t(struct kunit *test, const struct test_ ## t *p) \
 {							   		\
-	int err = 0;							\
-									\
 	check_one_op(t, fmt, add, "+", p->a, p->b, p->sum, p->s_of);	\
 	check_one_op(t, fmt, add, "+", p->b, p->a, p->sum, p->s_of);	\
 	check_one_op(t, fmt, sub, "-", p->a, p->b, p->diff, p->d_of);	\
 	check_one_op(t, fmt, mul, "*", p->a, p->b, p->prod, p->p_of);	\
 	check_one_op(t, fmt, mul, "*", p->b, p->a, p->prod, p->p_of);	\
-									\
-	return err;							\
 }									\
 									\
-static int __init test_ ## t ## _overflow(void) {			\
-	int err = 0;							\
+static void t ## _overflow_test(struct kunit *test) {			\
 	unsigned i;							\
 									\
-	pr_info("%-3s: %zu arithmetic tests\n", #t,			\
-		ARRAY_SIZE(t ## _tests));				\
 	for (i = 0; i < ARRAY_SIZE(t ## _tests); ++i)			\
-		err |= do_test_ ## t(&t ## _tests[i]);			\
-	return err;							\
+		do_test_ ## t(test, &t ## _tests[i]);			\
+	kunit_info(test, "%zu %s arithmetic tests finished\n",		\
+		ARRAY_SIZE(t ## _tests), #t);				\
 }
 
 DEFINE_TEST_FUNC(u8, "%d");
@@ -270,199 +260,176 @@ DEFINE_TEST_FUNC(u64, "%llu");
 DEFINE_TEST_FUNC(s64, "%lld");
 #endif
 
-static int __init test_overflow_calculation(void)
-{
-	int err = 0;
-
-	err |= test_u8_overflow();
-	err |= test_s8_overflow();
-	err |= test_u16_overflow();
-	err |= test_s16_overflow();
-	err |= test_u32_overflow();
-	err |= test_s32_overflow();
-#if BITS_PER_LONG == 64
-	err |= test_u64_overflow();
-	err |= test_s64_overflow();
-#endif
-
-	return err;
-}
-
-static int __init test_overflow_shift(void)
+static void overflow_shift_test(struct kunit *test)
 {
-	int err = 0;
+	int count = 0;
 
 /* Args are: value, shift, type, expected result, overflow expected */
-#define TEST_ONE_SHIFT(a, s, t, expect, of) ({				\
-	int __failed = 0;						\
+#define TEST_ONE_SHIFT(a, s, t, expect, of)	do {			\
 	typeof(a) __a = (a);						\
 	typeof(s) __s = (s);						\
 	t __e = (expect);						\
 	t __d;								\
 	bool __of = check_shl_overflow(__a, __s, &__d);			\
 	if (__of != of) {						\
-		pr_warn("expected (%s)(%s << %s) to%s overflow\n",	\
+		KUNIT_EXPECT_EQ_MSG(test, __of, of,			\
+			"expected (%s)(%s << %s) to%s overflow\n",	\
 			#t, #a, #s, of ? "" : " not");			\
-		__failed = 1;						\
 	} else if (!__of && __d != __e) {				\
-		pr_warn("expected (%s)(%s << %s) == %s\n",		\
+		KUNIT_EXPECT_EQ_MSG(test, __d, __e,			\
+			"expected (%s)(%s << %s) == %s\n",		\
 			#t, #a, #s, #expect);				\
 		if ((t)-1 < 0)						\
-			pr_warn("got %lld\n", (s64)__d);		\
+			kunit_info(test, "got %lld\n", (s64)__d);	\
 		else							\
-			pr_warn("got %llu\n", (u64)__d);		\
-		__failed = 1;						\
+			kunit_info(test, "got %llu\n", (u64)__d);	\
 	}								\
-	if (!__failed)							\
-		pr_info("ok: (%s)(%s << %s) == %s\n", #t, #a, #s,	\
-			of ? "overflow" : #expect);			\
-	__failed;							\
-})
+	count++;							\
+} while (0)
 
 	/* Sane shifts. */
-	err |= TEST_ONE_SHIFT(1, 0, u8, 1 << 0, false);
-	err |= TEST_ONE_SHIFT(1, 4, u8, 1 << 4, false);
-	err |= TEST_ONE_SHIFT(1, 7, u8, 1 << 7, false);
-	err |= TEST_ONE_SHIFT(0xF, 4, u8, 0xF << 4, false);
-	err |= TEST_ONE_SHIFT(1, 0, u16, 1 << 0, false);
-	err |= TEST_ONE_SHIFT(1, 10, u16, 1 << 10, false);
-	err |= TEST_ONE_SHIFT(1, 15, u16, 1 << 15, false);
-	err |= TEST_ONE_SHIFT(0xFF, 8, u16, 0xFF << 8, false);
-	err |= TEST_ONE_SHIFT(1, 0, int, 1 << 0, false);
-	err |= TEST_ONE_SHIFT(1, 16, int, 1 << 16, false);
-	err |= TEST_ONE_SHIFT(1, 30, int, 1 << 30, false);
-	err |= TEST_ONE_SHIFT(1, 0, s32, 1 << 0, false);
-	err |= TEST_ONE_SHIFT(1, 16, s32, 1 << 16, false);
-	err |= TEST_ONE_SHIFT(1, 30, s32, 1 << 30, false);
-	err |= TEST_ONE_SHIFT(1, 0, unsigned int, 1U << 0, false);
-	err |= TEST_ONE_SHIFT(1, 20, unsigned int, 1U << 20, false);
-	err |= TEST_ONE_SHIFT(1, 31, unsigned int, 1U << 31, false);
-	err |= TEST_ONE_SHIFT(0xFFFFU, 16, unsigned int, 0xFFFFU << 16, false);
-	err |= TEST_ONE_SHIFT(1, 0, u32, 1U << 0, false);
-	err |= TEST_ONE_SHIFT(1, 20, u32, 1U << 20, false);
-	err |= TEST_ONE_SHIFT(1, 31, u32, 1U << 31, false);
-	err |= TEST_ONE_SHIFT(0xFFFFU, 16, u32, 0xFFFFU << 16, false);
-	err |= TEST_ONE_SHIFT(1, 0, u64, 1ULL << 0, false);
-	err |= TEST_ONE_SHIFT(1, 40, u64, 1ULL << 40, false);
-	err |= TEST_ONE_SHIFT(1, 63, u64, 1ULL << 63, false);
-	err |= TEST_ONE_SHIFT(0xFFFFFFFFULL, 32, u64,
-			      0xFFFFFFFFULL << 32, false);
+	TEST_ONE_SHIFT(1, 0, u8, 1 << 0, false);
+	TEST_ONE_SHIFT(1, 4, u8, 1 << 4, false);
+	TEST_ONE_SHIFT(1, 7, u8, 1 << 7, false);
+	TEST_ONE_SHIFT(0xF, 4, u8, 0xF << 4, false);
+	TEST_ONE_SHIFT(1, 0, u16, 1 << 0, false);
+	TEST_ONE_SHIFT(1, 10, u16, 1 << 10, false);
+	TEST_ONE_SHIFT(1, 15, u16, 1 << 15, false);
+	TEST_ONE_SHIFT(0xFF, 8, u16, 0xFF << 8, false);
+	TEST_ONE_SHIFT(1, 0, int, 1 << 0, false);
+	TEST_ONE_SHIFT(1, 16, int, 1 << 16, false);
+	TEST_ONE_SHIFT(1, 30, int, 1 << 30, false);
+	TEST_ONE_SHIFT(1, 0, s32, 1 << 0, false);
+	TEST_ONE_SHIFT(1, 16, s32, 1 << 16, false);
+	TEST_ONE_SHIFT(1, 30, s32, 1 << 30, false);
+	TEST_ONE_SHIFT(1, 0, unsigned int, 1U << 0, false);
+	TEST_ONE_SHIFT(1, 20, unsigned int, 1U << 20, false);
+	TEST_ONE_SHIFT(1, 31, unsigned int, 1U << 31, false);
+	TEST_ONE_SHIFT(0xFFFFU, 16, unsigned int, 0xFFFFU << 16, false);
+	TEST_ONE_SHIFT(1, 0, u32, 1U << 0, false);
+	TEST_ONE_SHIFT(1, 20, u32, 1U << 20, false);
+	TEST_ONE_SHIFT(1, 31, u32, 1U << 31, false);
+	TEST_ONE_SHIFT(0xFFFFU, 16, u32, 0xFFFFU << 16, false);
+	TEST_ONE_SHIFT(1, 0, u64, 1ULL << 0, false);
+	TEST_ONE_SHIFT(1, 40, u64, 1ULL << 40, false);
+	TEST_ONE_SHIFT(1, 63, u64, 1ULL << 63, false);
+	TEST_ONE_SHIFT(0xFFFFFFFFULL, 32, u64, 0xFFFFFFFFULL << 32, false);
 
 	/* Sane shift: start and end with 0, without a too-wide shift. */
-	err |= TEST_ONE_SHIFT(0, 7, u8, 0, false);
-	err |= TEST_ONE_SHIFT(0, 15, u16, 0, false);
-	err |= TEST_ONE_SHIFT(0, 31, unsigned int, 0, false);
-	err |= TEST_ONE_SHIFT(0, 31, u32, 0, false);
-	err |= TEST_ONE_SHIFT(0, 63, u64, 0, false);
+	TEST_ONE_SHIFT(0, 7, u8, 0, false);
+	TEST_ONE_SHIFT(0, 15, u16, 0, false);
+	TEST_ONE_SHIFT(0, 31, unsigned int, 0, false);
+	TEST_ONE_SHIFT(0, 31, u32, 0, false);
+	TEST_ONE_SHIFT(0, 63, u64, 0, false);
 
 	/* Sane shift: start and end with 0, without reaching signed bit. */
-	err |= TEST_ONE_SHIFT(0, 6, s8, 0, false);
-	err |= TEST_ONE_SHIFT(0, 14, s16, 0, false);
-	err |= TEST_ONE_SHIFT(0, 30, int, 0, false);
-	err |= TEST_ONE_SHIFT(0, 30, s32, 0, false);
-	err |= TEST_ONE_SHIFT(0, 62, s64, 0, false);
+	TEST_ONE_SHIFT(0, 6, s8, 0, false);
+	TEST_ONE_SHIFT(0, 14, s16, 0, false);
+	TEST_ONE_SHIFT(0, 30, int, 0, false);
+	TEST_ONE_SHIFT(0, 30, s32, 0, false);
+	TEST_ONE_SHIFT(0, 62, s64, 0, false);
 
 	/* Overflow: shifted the bit off the end. */
-	err |= TEST_ONE_SHIFT(1, 8, u8, 0, true);
-	err |= TEST_ONE_SHIFT(1, 16, u16, 0, true);
-	err |= TEST_ONE_SHIFT(1, 32, unsigned int, 0, true);
-	err |= TEST_ONE_SHIFT(1, 32, u32, 0, true);
-	err |= TEST_ONE_SHIFT(1, 64, u64, 0, true);
+	TEST_ONE_SHIFT(1, 8, u8, 0, true);
+	TEST_ONE_SHIFT(1, 16, u16, 0, true);
+	TEST_ONE_SHIFT(1, 32, unsigned int, 0, true);
+	TEST_ONE_SHIFT(1, 32, u32, 0, true);
+	TEST_ONE_SHIFT(1, 64, u64, 0, true);
 
 	/* Overflow: shifted into the signed bit. */
-	err |= TEST_ONE_SHIFT(1, 7, s8, 0, true);
-	err |= TEST_ONE_SHIFT(1, 15, s16, 0, true);
-	err |= TEST_ONE_SHIFT(1, 31, int, 0, true);
-	err |= TEST_ONE_SHIFT(1, 31, s32, 0, true);
-	err |= TEST_ONE_SHIFT(1, 63, s64, 0, true);
+	TEST_ONE_SHIFT(1, 7, s8, 0, true);
+	TEST_ONE_SHIFT(1, 15, s16, 0, true);
+	TEST_ONE_SHIFT(1, 31, int, 0, true);
+	TEST_ONE_SHIFT(1, 31, s32, 0, true);
+	TEST_ONE_SHIFT(1, 63, s64, 0, true);
 
 	/* Overflow: high bit falls off unsigned types. */
 	/* 10010110 */
-	err |= TEST_ONE_SHIFT(150, 1, u8, 0, true);
+	TEST_ONE_SHIFT(150, 1, u8, 0, true);
 	/* 1000100010010110 */
-	err |= TEST_ONE_SHIFT(34966, 1, u16, 0, true);
+	TEST_ONE_SHIFT(34966, 1, u16, 0, true);
 	/* 10000100000010001000100010010110 */
-	err |= TEST_ONE_SHIFT(2215151766U, 1, u32, 0, true);
-	err |= TEST_ONE_SHIFT(2215151766U, 1, unsigned int, 0, true);
+	TEST_ONE_SHIFT(2215151766U, 1, u32, 0, true);
+	TEST_ONE_SHIFT(2215151766U, 1, unsigned int, 0, true);
 	/* 1000001000010000010000000100000010000100000010001000100010010110 */
-	err |= TEST_ONE_SHIFT(9372061470395238550ULL, 1, u64, 0, true);
+	TEST_ONE_SHIFT(9372061470395238550ULL, 1, u64, 0, true);
 
 	/* Overflow: bit shifted into signed bit on signed types. */
 	/* 01001011 */
-	err |= TEST_ONE_SHIFT(75, 1, s8, 0, true);
+	TEST_ONE_SHIFT(75, 1, s8, 0, true);
 	/* 0100010001001011 */
-	err |= TEST_ONE_SHIFT(17483, 1, s16, 0, true);
+	TEST_ONE_SHIFT(17483, 1, s16, 0, true);
 	/* 01000010000001000100010001001011 */
-	err |= TEST_ONE_SHIFT(1107575883, 1, s32, 0, true);
-	err |= TEST_ONE_SHIFT(1107575883, 1, int, 0, true);
+	TEST_ONE_SHIFT(1107575883, 1, s32, 0, true);
+	TEST_ONE_SHIFT(1107575883, 1, int, 0, true);
 	/* 0100000100001000001000000010000001000010000001000100010001001011 */
-	err |= TEST_ONE_SHIFT(4686030735197619275LL, 1, s64, 0, true);
+	TEST_ONE_SHIFT(4686030735197619275LL, 1, s64, 0, true);
 
 	/* Overflow: bit shifted past signed bit on signed types. */
 	/* 01001011 */
-	err |= TEST_ONE_SHIFT(75, 2, s8, 0, true);
+	TEST_ONE_SHIFT(75, 2, s8, 0, true);
 	/* 0100010001001011 */
-	err |= TEST_ONE_SHIFT(17483, 2, s16, 0, true);
+	TEST_ONE_SHIFT(17483, 2, s16, 0, true);
 	/* 01000010000001000100010001001011 */
-	err |= TEST_ONE_SHIFT(1107575883, 2, s32, 0, true);
-	err |= TEST_ONE_SHIFT(1107575883, 2, int, 0, true);
+	TEST_ONE_SHIFT(1107575883, 2, s32, 0, true);
+	TEST_ONE_SHIFT(1107575883, 2, int, 0, true);
 	/* 0100000100001000001000000010000001000010000001000100010001001011 */
-	err |= TEST_ONE_SHIFT(4686030735197619275LL, 2, s64, 0, true);
+	TEST_ONE_SHIFT(4686030735197619275LL, 2, s64, 0, true);
 
 	/* Overflow: values larger than destination type. */
-	err |= TEST_ONE_SHIFT(0x100, 0, u8, 0, true);
-	err |= TEST_ONE_SHIFT(0xFF, 0, s8, 0, true);
-	err |= TEST_ONE_SHIFT(0x10000U, 0, u16, 0, true);
-	err |= TEST_ONE_SHIFT(0xFFFFU, 0, s16, 0, true);
-	err |= TEST_ONE_SHIFT(0x100000000ULL, 0, u32, 0, true);
-	err |= TEST_ONE_SHIFT(0x100000000ULL, 0, unsigned int, 0, true);
-	err |= TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, s32, 0, true);
-	err |= TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, int, 0, true);
-	err |= TEST_ONE_SHIFT(0xFFFFFFFFFFFFFFFFULL, 0, s64, 0, true);
+	TEST_ONE_SHIFT(0x100, 0, u8, 0, true);
+	TEST_ONE_SHIFT(0xFF, 0, s8, 0, true);
+	TEST_ONE_SHIFT(0x10000U, 0, u16, 0, true);
+	TEST_ONE_SHIFT(0xFFFFU, 0, s16, 0, true);
+	TEST_ONE_SHIFT(0x100000000ULL, 0, u32, 0, true);
+	TEST_ONE_SHIFT(0x100000000ULL, 0, unsigned int, 0, true);
+	TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, s32, 0, true);
+	TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, int, 0, true);
+	TEST_ONE_SHIFT(0xFFFFFFFFFFFFFFFFULL, 0, s64, 0, true);
 
 	/* Nonsense: negative initial value. */
-	err |= TEST_ONE_SHIFT(-1, 0, s8, 0, true);
-	err |= TEST_ONE_SHIFT(-1, 0, u8, 0, true);
-	err |= TEST_ONE_SHIFT(-5, 0, s16, 0, true);
-	err |= TEST_ONE_SHIFT(-5, 0, u16, 0, true);
-	err |= TEST_ONE_SHIFT(-10, 0, int, 0, true);
-	err |= TEST_ONE_SHIFT(-10, 0, unsigned int, 0, true);
-	err |= TEST_ONE_SHIFT(-100, 0, s32, 0, true);
-	err |= TEST_ONE_SHIFT(-100, 0, u32, 0, true);
-	err |= TEST_ONE_SHIFT(-10000, 0, s64, 0, true);
-	err |= TEST_ONE_SHIFT(-10000, 0, u64, 0, true);
+	TEST_ONE_SHIFT(-1, 0, s8, 0, true);
+	TEST_ONE_SHIFT(-1, 0, u8, 0, true);
+	TEST_ONE_SHIFT(-5, 0, s16, 0, true);
+	TEST_ONE_SHIFT(-5, 0, u16, 0, true);
+	TEST_ONE_SHIFT(-10, 0, int, 0, true);
+	TEST_ONE_SHIFT(-10, 0, unsigned int, 0, true);
+	TEST_ONE_SHIFT(-100, 0, s32, 0, true);
+	TEST_ONE_SHIFT(-100, 0, u32, 0, true);
+	TEST_ONE_SHIFT(-10000, 0, s64, 0, true);
+	TEST_ONE_SHIFT(-10000, 0, u64, 0, true);
 
 	/* Nonsense: negative shift values. */
-	err |= TEST_ONE_SHIFT(0, -5, s8, 0, true);
-	err |= TEST_ONE_SHIFT(0, -5, u8, 0, true);
-	err |= TEST_ONE_SHIFT(0, -10, s16, 0, true);
-	err |= TEST_ONE_SHIFT(0, -10, u16, 0, true);
-	err |= TEST_ONE_SHIFT(0, -15, int, 0, true);
-	err |= TEST_ONE_SHIFT(0, -15, unsigned int, 0, true);
-	err |= TEST_ONE_SHIFT(0, -20, s32, 0, true);
-	err |= TEST_ONE_SHIFT(0, -20, u32, 0, true);
-	err |= TEST_ONE_SHIFT(0, -30, s64, 0, true);
-	err |= TEST_ONE_SHIFT(0, -30, u64, 0, true);
+	TEST_ONE_SHIFT(0, -5, s8, 0, true);
+	TEST_ONE_SHIFT(0, -5, u8, 0, true);
+	TEST_ONE_SHIFT(0, -10, s16, 0, true);
+	TEST_ONE_SHIFT(0, -10, u16, 0, true);
+	TEST_ONE_SHIFT(0, -15, int, 0, true);
+	TEST_ONE_SHIFT(0, -15, unsigned int, 0, true);
+	TEST_ONE_SHIFT(0, -20, s32, 0, true);
+	TEST_ONE_SHIFT(0, -20, u32, 0, true);
+	TEST_ONE_SHIFT(0, -30, s64, 0, true);
+	TEST_ONE_SHIFT(0, -30, u64, 0, true);
 
 	/* Overflow: shifted at or beyond entire type's bit width. */
-	err |= TEST_ONE_SHIFT(0, 8, u8, 0, true);
-	err |= TEST_ONE_SHIFT(0, 9, u8, 0, true);
-	err |= TEST_ONE_SHIFT(0, 8, s8, 0, true);
-	err |= TEST_ONE_SHIFT(0, 9, s8, 0, true);
-	err |= TEST_ONE_SHIFT(0, 16, u16, 0, true);
-	err |= TEST_ONE_SHIFT(0, 17, u16, 0, true);
-	err |= TEST_ONE_SHIFT(0, 16, s16, 0, true);
-	err |= TEST_ONE_SHIFT(0, 17, s16, 0, true);
-	err |= TEST_ONE_SHIFT(0, 32, u32, 0, true);
-	err |= TEST_ONE_SHIFT(0, 33, u32, 0, true);
-	err |= TEST_ONE_SHIFT(0, 32, int, 0, true);
-	err |= TEST_ONE_SHIFT(0, 33, int, 0, true);
-	err |= TEST_ONE_SHIFT(0, 32, s32, 0, true);
-	err |= TEST_ONE_SHIFT(0, 33, s32, 0, true);
-	err |= TEST_ONE_SHIFT(0, 64, u64, 0, true);
-	err |= TEST_ONE_SHIFT(0, 65, u64, 0, true);
-	err |= TEST_ONE_SHIFT(0, 64, s64, 0, true);
-	err |= TEST_ONE_SHIFT(0, 65, s64, 0, true);
+	TEST_ONE_SHIFT(0, 8, u8, 0, true);
+	TEST_ONE_SHIFT(0, 9, u8, 0, true);
+	TEST_ONE_SHIFT(0, 8, s8, 0, true);
+	TEST_ONE_SHIFT(0, 9, s8, 0, true);
+	TEST_ONE_SHIFT(0, 16, u16, 0, true);
+	TEST_ONE_SHIFT(0, 17, u16, 0, true);
+	TEST_ONE_SHIFT(0, 16, s16, 0, true);
+	TEST_ONE_SHIFT(0, 17, s16, 0, true);
+	TEST_ONE_SHIFT(0, 32, u32, 0, true);
+	TEST_ONE_SHIFT(0, 33, u32, 0, true);
+	TEST_ONE_SHIFT(0, 32, int, 0, true);
+	TEST_ONE_SHIFT(0, 33, int, 0, true);
+	TEST_ONE_SHIFT(0, 32, s32, 0, true);
+	TEST_ONE_SHIFT(0, 33, s32, 0, true);
+	TEST_ONE_SHIFT(0, 64, u64, 0, true);
+	TEST_ONE_SHIFT(0, 65, u64, 0, true);
+	TEST_ONE_SHIFT(0, 64, s64, 0, true);
+	TEST_ONE_SHIFT(0, 65, s64, 0, true);
 
 	/*
 	 * Corner case: for unsigned types, we fail when we've shifted
@@ -473,13 +440,14 @@ static int __init test_overflow_shift(void)
 	 * signed bit). So, for now, we will test this condition but
 	 * mark it as not expected to overflow.
 	 */
-	err |= TEST_ONE_SHIFT(0, 7, s8, 0, false);
-	err |= TEST_ONE_SHIFT(0, 15, s16, 0, false);
-	err |= TEST_ONE_SHIFT(0, 31, int, 0, false);
-	err |= TEST_ONE_SHIFT(0, 31, s32, 0, false);
-	err |= TEST_ONE_SHIFT(0, 63, s64, 0, false);
-
-	return err;
+	TEST_ONE_SHIFT(0, 7, s8, 0, false);
+	TEST_ONE_SHIFT(0, 15, s16, 0, false);
+	TEST_ONE_SHIFT(0, 31, int, 0, false);
+	TEST_ONE_SHIFT(0, 31, s32, 0, false);
+	TEST_ONE_SHIFT(0, 63, s64, 0, false);
+
+	kunit_info(test, "%d shift tests finished\n", count);
+#undef TEST_ONE_SHIFT
 }
 
 /*
@@ -499,7 +467,7 @@ static int __init test_overflow_shift(void)
 #define TEST_SIZE		(5 * 4096)
 
 #define DEFINE_TEST_ALLOC(func, free_func, want_arg, want_gfp, want_node)\
-static int __init test_ ## func (void *arg)				\
+static void test_ ## func (struct kunit *test, void *arg)		\
 {									\
 	volatile size_t a = TEST_SIZE;					\
 	volatile size_t b = (SIZE_MAX / TEST_SIZE) + 1;			\
@@ -507,31 +475,24 @@ static int __init test_ ## func (void *arg)				\
 									\
 	/* Tiny allocation test. */					\
 	ptr = alloc ## want_arg ## want_gfp ## want_node (func, arg, 1);\
-	if (!ptr) {							\
-		pr_warn(#func " failed regular allocation?!\n");	\
-		return 1;						\
-	}								\
+	KUNIT_ASSERT_NOT_ERR_OR_NULL_MSG(test, ptr,			\
+			    #func " failed regular allocation?!\n");	\
 	free ## want_arg (free_func, arg, ptr);				\
 									\
 	/* Wrapped allocation test. */					\
 	ptr = alloc ## want_arg ## want_gfp ## want_node (func, arg,	\
 							  a * b);	\
-	if (!ptr) {							\
-		pr_warn(#func " unexpectedly failed bad wrapping?!\n");	\
-		return 1;						\
-	}								\
+	KUNIT_ASSERT_NOT_ERR_OR_NULL_MSG(test, ptr,			\
+			    #func " unexpectedly failed bad wrapping?!\n"); \
 	free ## want_arg (free_func, arg, ptr);				\
 									\
 	/* Saturated allocation test. */				\
 	ptr = alloc ## want_arg ## want_gfp ## want_node (func, arg,	\
 						   array_size(a, b));	\
 	if (ptr) {							\
-		pr_warn(#func " missed saturation!\n");			\
+		KUNIT_FAIL(test, #func " missed saturation!\n");	\
 		free ## want_arg (free_func, arg, ptr);			\
-		return 1;						\
 	}								\
-	pr_info(#func " detected saturation\n");			\
-	return 0;							\
 }
 
 /*
@@ -544,10 +505,7 @@ DEFINE_TEST_ALLOC(kmalloc,	 kfree,	     0, 1, 0);
 DEFINE_TEST_ALLOC(kmalloc_node,	 kfree,	     0, 1, 1);
 DEFINE_TEST_ALLOC(kzalloc,	 kfree,	     0, 1, 0);
 DEFINE_TEST_ALLOC(kzalloc_node,  kfree,	     0, 1, 1);
-DEFINE_TEST_ALLOC(vmalloc,	 vfree,	     0, 0, 0);
-DEFINE_TEST_ALLOC(vmalloc_node,  vfree,	     0, 0, 1);
-DEFINE_TEST_ALLOC(vzalloc,	 vfree,	     0, 0, 0);
-DEFINE_TEST_ALLOC(vzalloc_node,  vfree,	     0, 0, 1);
+DEFINE_TEST_ALLOC(__vmalloc,	 vfree,	     0, 1, 0);
 DEFINE_TEST_ALLOC(kvmalloc,	 kvfree,     0, 1, 0);
 DEFINE_TEST_ALLOC(kvmalloc_node, kvfree,     0, 1, 1);
 DEFINE_TEST_ALLOC(kvzalloc,	 kvfree,     0, 1, 0);
@@ -555,60 +513,158 @@ DEFINE_TEST_ALLOC(kvzalloc_node, kvfree,     0, 1, 1);
 DEFINE_TEST_ALLOC(devm_kmalloc,  devm_kfree, 1, 1, 0);
 DEFINE_TEST_ALLOC(devm_kzalloc,  devm_kfree, 1, 1, 0);
 
-static int __init test_overflow_allocation(void)
+static void overflow_allocation_test(struct kunit *test)
 {
 	const char device_name[] = "overflow-test";
 	struct device *dev;
-	int err = 0;
+	int count = 0;
+
+#define check_allocation_overflow(alloc)	do {	\
+	count++;					\
+	test_ ## alloc(test, dev);			\
+} while (0)
 
 	/* Create dummy device for devm_kmalloc()-family tests. */
 	dev = root_device_register(device_name);
-	if (IS_ERR(dev)) {
-		pr_warn("Cannot register test device\n");
-		return 1;
-	}
-
-	err |= test_kmalloc(NULL);
-	err |= test_kmalloc_node(NULL);
-	err |= test_kzalloc(NULL);
-	err |= test_kzalloc_node(NULL);
-	err |= test_kvmalloc(NULL);
-	err |= test_kvmalloc_node(NULL);
-	err |= test_kvzalloc(NULL);
-	err |= test_kvzalloc_node(NULL);
-	err |= test_vmalloc(NULL);
-	err |= test_vmalloc_node(NULL);
-	err |= test_vzalloc(NULL);
-	err |= test_vzalloc_node(NULL);
-	err |= test_devm_kmalloc(dev);
-	err |= test_devm_kzalloc(dev);
+	KUNIT_ASSERT_FALSE_MSG(test, IS_ERR(dev),
+			       "Cannot register test device\n");
+
+	check_allocation_overflow(kmalloc);
+	check_allocation_overflow(kmalloc_node);
+	check_allocation_overflow(kzalloc);
+	check_allocation_overflow(kzalloc_node);
+	check_allocation_overflow(__vmalloc);
+	check_allocation_overflow(kvmalloc);
+	check_allocation_overflow(kvmalloc_node);
+	check_allocation_overflow(kvzalloc);
+	check_allocation_overflow(kvzalloc_node);
+	check_allocation_overflow(devm_kmalloc);
+	check_allocation_overflow(devm_kzalloc);
 
 	device_unregister(dev);
 
-	return err;
+	kunit_info(test, "%d allocation overflow tests finished\n", count);
+#undef check_allocation_overflow
 }
 
-static int __init test_module_init(void)
+struct __test_flex_array {
+	unsigned long flags;
+	size_t count;
+	unsigned long data[];
+};
+
+static void overflow_size_helpers_test(struct kunit *test)
 {
-	int err = 0;
+	/* Make sure struct_size() can be used in a constant expression. */
+	u8 ce_array[struct_size((struct __test_flex_array *)0, data, 55)];
+	struct __test_flex_array *obj;
+	int count = 0;
+	int var;
+	volatile int unconst = 0;
+
+	/* Verify constant expression against runtime version. */
+	var = 55;
+	OPTIMIZER_HIDE_VAR(var);
+	KUNIT_EXPECT_EQ(test, sizeof(ce_array), struct_size(obj, data, var));
+
+#define check_one_size_helper(expected, func, args...)	do {	\
+	size_t _r = func(args);					\
+	KUNIT_EXPECT_EQ_MSG(test, _r, expected,			\
+		"expected " #func "(" #args ") to return %zu but got %zu instead\n", \
+		(size_t)(expected), _r);			\
+	count++;						\
+} while (0)
 
-	err |= test_overflow_calculation();
-	err |= test_overflow_shift();
-	err |= test_overflow_allocation();
+	var = 4;
+	check_one_size_helper(20,	size_mul, var++, 5);
+	check_one_size_helper(20,	size_mul, 4, var++);
+	check_one_size_helper(0,	size_mul, 0, 3);
+	check_one_size_helper(0,	size_mul, 3, 0);
+	check_one_size_helper(6,	size_mul, 2, 3);
+	check_one_size_helper(SIZE_MAX,	size_mul, SIZE_MAX,  1);
+	check_one_size_helper(SIZE_MAX,	size_mul, SIZE_MAX,  3);
+	check_one_size_helper(SIZE_MAX,	size_mul, SIZE_MAX, -3);
+
+	var = 4;
+	check_one_size_helper(9,	size_add, var++, 5);
+	check_one_size_helper(9,	size_add, 4, var++);
+	check_one_size_helper(9,	size_add, 9, 0);
+	check_one_size_helper(9,	size_add, 0, 9);
+	check_one_size_helper(5,	size_add, 2, 3);
+	check_one_size_helper(SIZE_MAX, size_add, SIZE_MAX,  1);
+	check_one_size_helper(SIZE_MAX, size_add, SIZE_MAX,  3);
+	check_one_size_helper(SIZE_MAX, size_add, SIZE_MAX, -3);
+
+	var = 4;
+	check_one_size_helper(1,	size_sub, var--, 3);
+	check_one_size_helper(1,	size_sub, 4, var--);
+	check_one_size_helper(1,	size_sub, 3, 2);
+	check_one_size_helper(9,	size_sub, 9, 0);
+	check_one_size_helper(SIZE_MAX, size_sub, 9, -3);
+	check_one_size_helper(SIZE_MAX, size_sub, 0, 9);
+	check_one_size_helper(SIZE_MAX, size_sub, 2, 3);
+	check_one_size_helper(SIZE_MAX, size_sub, SIZE_MAX,  0);
+	check_one_size_helper(SIZE_MAX, size_sub, SIZE_MAX, 10);
+	check_one_size_helper(SIZE_MAX, size_sub, 0,  SIZE_MAX);
+	check_one_size_helper(SIZE_MAX, size_sub, 14, SIZE_MAX);
+	check_one_size_helper(SIZE_MAX - 2, size_sub, SIZE_MAX - 1,  1);
+	check_one_size_helper(SIZE_MAX - 4, size_sub, SIZE_MAX - 1,  3);
+	check_one_size_helper(1,		size_sub, SIZE_MAX - 1, -3);
+
+	var = 4;
+	check_one_size_helper(4 * sizeof(*obj->data),
+			      flex_array_size, obj, data, var++);
+	check_one_size_helper(5 * sizeof(*obj->data),
+			      flex_array_size, obj, data, var++);
+	check_one_size_helper(0, flex_array_size, obj, data, 0 + unconst);
+	check_one_size_helper(sizeof(*obj->data),
+			      flex_array_size, obj, data, 1 + unconst);
+	check_one_size_helper(7 * sizeof(*obj->data),
+			      flex_array_size, obj, data, 7 + unconst);
+	check_one_size_helper(SIZE_MAX,
+			      flex_array_size, obj, data, -1 + unconst);
+	check_one_size_helper(SIZE_MAX,
+			      flex_array_size, obj, data, SIZE_MAX - 4 + unconst);
+
+	var = 4;
+	check_one_size_helper(sizeof(*obj) + (4 * sizeof(*obj->data)),
+			      struct_size, obj, data, var++);
+	check_one_size_helper(sizeof(*obj) + (5 * sizeof(*obj->data)),
+			      struct_size, obj, data, var++);
+	check_one_size_helper(sizeof(*obj), struct_size, obj, data, 0 + unconst);
+	check_one_size_helper(sizeof(*obj) + sizeof(*obj->data),
+			      struct_size, obj, data, 1 + unconst);
+	check_one_size_helper(SIZE_MAX,
+			      struct_size, obj, data, -3 + unconst);
+	check_one_size_helper(SIZE_MAX,
+			      struct_size, obj, data, SIZE_MAX - 3 + unconst);
+
+	kunit_info(test, "%d overflow size helper tests finished\n", count);
+#undef check_one_size_helper
+}
 
-	if (err) {
-		pr_warn("FAIL!\n");
-		err = -EINVAL;
-	} else {
-		pr_info("all tests passed\n");
-	}
+static struct kunit_case overflow_test_cases[] = {
+	KUNIT_CASE(u8_overflow_test),
+	KUNIT_CASE(s8_overflow_test),
+	KUNIT_CASE(u16_overflow_test),
+	KUNIT_CASE(s16_overflow_test),
+	KUNIT_CASE(u32_overflow_test),
+	KUNIT_CASE(s32_overflow_test),
+#if BITS_PER_LONG == 64
+	KUNIT_CASE(u64_overflow_test),
+	KUNIT_CASE(s64_overflow_test),
+#endif
+	KUNIT_CASE(overflow_shift_test),
+	KUNIT_CASE(overflow_allocation_test),
+	KUNIT_CASE(overflow_size_helpers_test),
+	{}
+};
 
-	return err;
-}
+static struct kunit_suite overflow_test_suite = {
+	.name = "overflow",
+	.test_cases = overflow_test_cases,
+};
 
-static void __exit test_module_exit(void)
-{ }
+kunit_test_suite(overflow_test_suite);
 
-module_init(test_module_init);
-module_exit(test_module_exit);
 MODULE_LICENSE("Dual MIT/GPL");
diff --git a/lib/test_stackinit.c b/lib/stackinit_kunit.c
index a3c74e6a21ff..35c69aa425b2 100644
--- a/lib/test_stackinit.c
+++ b/lib/stackinit_kunit.c
@@ -2,76 +2,21 @@
 /*
  * Test cases for compiler-based stack variable zeroing via
  * -ftrivial-auto-var-init={zero,pattern} or CONFIG_GCC_PLUGIN_STRUCTLEAK*.
+ * For example, see:
+ * https://www.kernel.org/doc/html/latest/dev-tools/kunit/kunit-tool.html#configuring-building-and-running-tests
+ *	./tools/testing/kunit/kunit.py run stackinit [--raw_output] \
+ *		--make_option LLVM=1 \
+ *		--kconfig_add CONFIG_INIT_STACK_ALL_ZERO=y
  *
- * External build example:
- *	clang -O2 -Wall -ftrivial-auto-var-init=pattern \
- *		-o test_stackinit test_stackinit.c
  */
-#ifdef __KERNEL__
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <kunit/test.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/string.h>
 
-#else
-
-/* Userspace headers. */
-#include <stdio.h>
-#include <stdint.h>
-#include <string.h>
-#include <stdbool.h>
-#include <errno.h>
-#include <sys/types.h>
-
-/* Linux kernel-ism stubs for stand-alone userspace build. */
-#define KBUILD_MODNAME		"stackinit"
-#define pr_fmt(fmt)		KBUILD_MODNAME ": " fmt
-#define pr_err(fmt, ...)	fprintf(stderr, pr_fmt(fmt), ##__VA_ARGS__)
-#define pr_warn(fmt, ...)	fprintf(stderr, pr_fmt(fmt), ##__VA_ARGS__)
-#define pr_info(fmt, ...)	fprintf(stdout, pr_fmt(fmt), ##__VA_ARGS__)
-#define __init			/**/
-#define __exit			/**/
-#define __user			/**/
-#define noinline		__attribute__((__noinline__))
-#define __aligned(x)		__attribute__((__aligned__(x)))
-#ifdef __clang__
-# define __compiletime_error(message) /**/
-#else
-# define __compiletime_error(message) __attribute__((__error__(message)))
-#endif
-#define __compiletime_assert(condition, msg, prefix, suffix)		\
-	do {								\
-		extern void prefix ## suffix(void) __compiletime_error(msg); \
-		if (!(condition))					\
-			prefix ## suffix();				\
-	} while (0)
-#define _compiletime_assert(condition, msg, prefix, suffix) \
-	__compiletime_assert(condition, msg, prefix, suffix)
-#define compiletime_assert(condition, msg) \
-	_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
-#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
-#define BUILD_BUG_ON(condition) \
-	BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
-typedef uint8_t			u8;
-typedef uint16_t		u16;
-typedef uint32_t		u32;
-typedef uint64_t		u64;
-
-#define module_init(func)	static int (*do_init)(void) = func
-#define module_exit(func)	static void (*do_exit)(void) = func
-#define MODULE_LICENSE(str)	int main(void) {		\
-					int rc;			\
-					/* License: str */	\
-					rc = do_init();		\
-					if (rc == 0)		\
-						do_exit();	\
-					return rc;		\
-				}
-
-#endif /* __KERNEL__ */
-
 /* Exfiltration buffer. */
 #define MAX_VAR_SIZE	128
 static u8 check_buf[MAX_VAR_SIZE];
@@ -201,7 +146,7 @@ static bool range_contains(char *haystack_start, size_t haystack_size,
  */
 #define DEFINE_TEST_DRIVER(name, var_type, which, xfail)	\
 /* Returns 0 on success, 1 on failure. */			\
-static noinline __init int test_ ## name (void)			\
+static noinline void test_ ## name (struct kunit *test)		\
 {								\
 	var_type zero INIT_CLONE_ ## which;			\
 	int ignored;						\
@@ -220,10 +165,8 @@ static noinline __init int test_ ## name (void)			\
 	/* Verify all bytes overwritten with 0xFF. */		\
 	for (sum = 0, i = 0; i < target_size; i++)		\
 		sum += (check_buf[i] != 0xFF);			\
-	if (sum) {						\
-		pr_err(#name ": leaf fill was not 0xFF!?\n");	\
-		return 1;					\
-	}							\
+	KUNIT_ASSERT_EQ_MSG(test, sum, 0,			\
+			    "leaf fill was not 0xFF!?\n");	\
 	/* Clear entire check buffer for later bit tests. */	\
 	memset(check_buf, 0x00, sizeof(check_buf));		\
 	/* Extract stack-defined variable contents. */		\
@@ -231,32 +174,29 @@ static noinline __init int test_ ## name (void)			\
 				FETCH_ARG_ ## which(zero));	\
 								\
 	/* Validate that compiler lined up fill and target. */	\
-	if (!range_contains(fill_start, fill_size,		\
-			    target_start, target_size)) {	\
-		pr_err(#name ": stack fill missed target!?\n");	\
-		pr_err(#name ": fill %zu wide\n", fill_size);	\
-		pr_err(#name ": target offset by %d\n",	\
-			(int)((ssize_t)(uintptr_t)fill_start -	\
-			(ssize_t)(uintptr_t)target_start));	\
-		return 1;					\
-	}							\
+	KUNIT_ASSERT_TRUE_MSG(test,				\
+		range_contains(fill_start, fill_size,		\
+			    target_start, target_size),		\
+		"stack fill missed target!? "			\
+		"(fill %zu wide, target offset by %d)\n",	\
+		fill_size,					\
+		(int)((ssize_t)(uintptr_t)fill_start -		\
+		      (ssize_t)(uintptr_t)target_start));	\
 								\
 	/* Look for any bytes still 0xFF in check region. */	\
 	for (sum = 0, i = 0; i < target_size; i++)		\
 		sum += (check_buf[i] == 0xFF);			\
 								\
-	if (sum == 0) {						\
-		pr_info(#name " ok\n");				\
-		return 0;					\
-	} else {						\
-		pr_warn(#name " %sFAIL (uninit bytes: %d)\n",	\
-			(xfail) ? "X" : "", sum);		\
-		return (xfail) ? 0 : 1;				\
-	}							\
+	if (sum != 0 && xfail)					\
+		kunit_skip(test,				\
+			   "XFAIL uninit bytes: %d\n",		\
+			   sum);				\
+	KUNIT_ASSERT_EQ_MSG(test, sum, 0,			\
+		"uninit bytes: %d\n", sum);			\
 }
 #define DEFINE_TEST(name, var_type, which, init_level, xfail)	\
 /* no-op to force compiler into ignoring "uninitialized" vars */\
-static noinline __init DO_NOTHING_TYPE_ ## which(var_type)	\
+static noinline DO_NOTHING_TYPE_ ## which(var_type)		\
 do_nothing_ ## name(var_type *ptr)				\
 {								\
 	/* Will always be true, but compiler doesn't know. */	\
@@ -265,9 +205,8 @@ do_nothing_ ## name(var_type *ptr)				\
 	else							\
 		return DO_NOTHING_RETURN_ ## which(ptr + 1);	\
 }								\
-static noinline __init int leaf_ ## name(unsigned long sp,	\
-					 bool fill,		\
-					 var_type *arg)		\
+static noinline int leaf_ ## name(unsigned long sp, bool fill,	\
+				  var_type *arg)		\
 {								\
 	char buf[VAR_BUFFER];					\
 	var_type var						\
@@ -341,6 +280,27 @@ struct test_user {
 	unsigned long four;
 };
 
+#define ALWAYS_PASS	WANT_SUCCESS
+#define ALWAYS_FAIL	XFAIL
+
+#ifdef CONFIG_INIT_STACK_NONE
+# define USER_PASS	XFAIL
+# define BYREF_PASS	XFAIL
+# define STRONG_PASS	XFAIL
+#elif defined(CONFIG_GCC_PLUGIN_STRUCTLEAK_USER)
+# define USER_PASS	WANT_SUCCESS
+# define BYREF_PASS	XFAIL
+# define STRONG_PASS	XFAIL
+#elif defined(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF)
+# define USER_PASS	WANT_SUCCESS
+# define BYREF_PASS	WANT_SUCCESS
+# define STRONG_PASS	XFAIL
+#else
+# define USER_PASS	WANT_SUCCESS
+# define BYREF_PASS	WANT_SUCCESS
+# define STRONG_PASS	WANT_SUCCESS
+#endif
+
 #define DEFINE_SCALAR_TEST(name, init, xfail)			\
 		DEFINE_TEST(name ## _ ## init, name, SCALAR,	\
 			    init, xfail)
@@ -364,27 +324,26 @@ struct test_user {
 		DEFINE_STRUCT_TEST(trailing_hole, init, xfail);	\
 		DEFINE_STRUCT_TEST(packed, init, xfail)
 
-#define DEFINE_STRUCT_INITIALIZER_TESTS(base)			\
+#define DEFINE_STRUCT_INITIALIZER_TESTS(base, xfail)		\
 		DEFINE_STRUCT_TESTS(base ## _ ## partial,	\
-				    WANT_SUCCESS);		\
-		DEFINE_STRUCT_TESTS(base ## _ ## all,		\
-				    WANT_SUCCESS)
+				    xfail);			\
+		DEFINE_STRUCT_TESTS(base ## _ ## all, xfail)
 
 /* These should be fully initialized all the time! */
-DEFINE_SCALAR_TESTS(zero, WANT_SUCCESS);
-DEFINE_STRUCT_TESTS(zero, WANT_SUCCESS);
+DEFINE_SCALAR_TESTS(zero, ALWAYS_PASS);
+DEFINE_STRUCT_TESTS(zero, ALWAYS_PASS);
 /* Struct initializers: padding may be left uninitialized. */
-DEFINE_STRUCT_INITIALIZER_TESTS(static);
-DEFINE_STRUCT_INITIALIZER_TESTS(dynamic);
-DEFINE_STRUCT_INITIALIZER_TESTS(runtime);
-DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static);
-DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic);
-DEFINE_STRUCT_TESTS(assigned_copy, XFAIL);
+DEFINE_STRUCT_INITIALIZER_TESTS(static, STRONG_PASS);
+DEFINE_STRUCT_INITIALIZER_TESTS(dynamic, STRONG_PASS);
+DEFINE_STRUCT_INITIALIZER_TESTS(runtime, STRONG_PASS);
+DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static, STRONG_PASS);
+DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);
+DEFINE_STRUCT_TESTS(assigned_copy, ALWAYS_FAIL);
 /* No initialization without compiler instrumentation. */
-DEFINE_SCALAR_TESTS(none, WANT_SUCCESS);
-DEFINE_STRUCT_TESTS(none, WANT_SUCCESS);
+DEFINE_SCALAR_TESTS(none, STRONG_PASS);
+DEFINE_STRUCT_TESTS(none, BYREF_PASS);
 /* Initialization of members with __user attribute. */
-DEFINE_TEST(user, struct test_user, STRUCT, none, WANT_SUCCESS);
+DEFINE_TEST(user, struct test_user, STRUCT, none, USER_PASS);
 
 /*
  * Check two uses through a variable declaration outside either path,
@@ -398,7 +357,7 @@ static int noinline __leaf_switch_none(int path, bool fill)
 		 * This is intentionally unreachable. To silence the
 		 * warning, build with -Wno-switch-unreachable
 		 */
-		uint64_t var;
+		uint64_t var[10];
 
 	case 1:
 		target_start = &var;
@@ -423,19 +382,19 @@ static int noinline __leaf_switch_none(int path, bool fill)
 		memcpy(check_buf, target_start, target_size);
 		break;
 	default:
-		var = 5;
-		return var & forced_mask;
+		var[1] = 5;
+		return var[1] & forced_mask;
 	}
 	return 0;
 }
 
-static noinline __init int leaf_switch_1_none(unsigned long sp, bool fill,
+static noinline int leaf_switch_1_none(unsigned long sp, bool fill,
 					      uint64_t *arg)
 {
 	return __leaf_switch_none(1, fill);
 }
 
-static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill,
+static noinline int leaf_switch_2_none(unsigned long sp, bool fill,
 					      uint64_t *arg)
 {
 	return __leaf_switch_none(2, fill);
@@ -447,68 +406,56 @@ static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill,
  * non-code areas (i.e. in a switch statement before the first "case").
  * https://bugs.llvm.org/show_bug.cgi?id=44916
  */
-DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, XFAIL);
-DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, XFAIL);
-
-static int __init test_stackinit_init(void)
-{
-	unsigned int failures = 0;
-
-#define test_scalars(init)	do {				\
-		failures += test_u8_ ## init ();		\
-		failures += test_u16_ ## init ();		\
-		failures += test_u32_ ## init ();		\
-		failures += test_u64_ ## init ();		\
-		failures += test_char_array_ ## init ();	\
-	} while (0)
-
-#define test_structs(init)	do {				\
-		failures += test_small_hole_ ## init ();	\
-		failures += test_big_hole_ ## init ();		\
-		failures += test_trailing_hole_ ## init ();	\
-		failures += test_packed_ ## init ();		\
-	} while (0)
-
+DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, ALWAYS_FAIL);
+DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, ALWAYS_FAIL);
+
+#define KUNIT_test_scalars(init)			\
+		KUNIT_CASE(test_u8_ ## init),		\
+		KUNIT_CASE(test_u16_ ## init),		\
+		KUNIT_CASE(test_u32_ ## init),		\
+		KUNIT_CASE(test_u64_ ## init),		\
+		KUNIT_CASE(test_char_array_ ## init)
+
+#define KUNIT_test_structs(init)			\
+		KUNIT_CASE(test_small_hole_ ## init),	\
+		KUNIT_CASE(test_big_hole_ ## init),	\
+		KUNIT_CASE(test_trailing_hole_ ## init),\
+		KUNIT_CASE(test_packed_ ## init)	\
+
+static struct kunit_case stackinit_test_cases[] = {
 	/* These are explicitly initialized and should always pass. */
-	test_scalars(zero);
-	test_structs(zero);
+	KUNIT_test_scalars(zero),
+	KUNIT_test_structs(zero),
 	/* Padding here appears to be accidentally always initialized? */
-	test_structs(dynamic_partial);
-	test_structs(assigned_dynamic_partial);
+	KUNIT_test_structs(dynamic_partial),
+	KUNIT_test_structs(assigned_dynamic_partial),
 	/* Padding initialization depends on compiler behaviors. */
-	test_structs(static_partial);
-	test_structs(static_all);
-	test_structs(dynamic_all);
-	test_structs(runtime_partial);
-	test_structs(runtime_all);
-	test_structs(assigned_static_partial);
-	test_structs(assigned_static_all);
-	test_structs(assigned_dynamic_all);
+	KUNIT_test_structs(static_partial),
+	KUNIT_test_structs(static_all),
+	KUNIT_test_structs(dynamic_all),
+	KUNIT_test_structs(runtime_partial),
+	KUNIT_test_structs(runtime_all),
+	KUNIT_test_structs(assigned_static_partial),
+	KUNIT_test_structs(assigned_static_all),
+	KUNIT_test_structs(assigned_dynamic_all),
 	/* Everything fails this since it effectively performs a memcpy(). */
-	test_structs(assigned_copy);
-
+	KUNIT_test_structs(assigned_copy),
 	/* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
-	test_scalars(none);
-	failures += test_switch_1_none();
-	failures += test_switch_2_none();
-
+	KUNIT_test_scalars(none),
+	KUNIT_CASE(test_switch_1_none),
+	KUNIT_CASE(test_switch_2_none),
 	/* STRUCTLEAK_BYREF should cover from here down. */
-	test_structs(none);
-
+	KUNIT_test_structs(none),
 	/* STRUCTLEAK will only cover this. */
-	failures += test_user();
-
-	if (failures == 0)
-		pr_info("all tests passed!\n");
-	else
-		pr_err("failures: %u\n", failures);
+	KUNIT_CASE(test_user),
+	{}
+};
 
-	return failures ? -EINVAL : 0;
-}
-module_init(test_stackinit_init);
+static struct kunit_suite stackinit_test_suite = {
+	.name = "stackinit",
+	.test_cases = stackinit_test_cases,
+};
 
-static void __exit test_stackinit_exit(void)
-{ }
-module_exit(test_stackinit_exit);
+kunit_test_suites(&stackinit_test_suite);
 
 MODULE_LICENSE("GPL");
diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang
index 51fc23e2e9e5..87285b76adb2 100644
--- a/scripts/Makefile.clang
+++ b/scripts/Makefile.clang
@@ -10,6 +10,7 @@ CLANG_TARGET_FLAGS_powerpc	:= powerpc64le-linux-gnu
 CLANG_TARGET_FLAGS_riscv	:= riscv64-linux-gnu
 CLANG_TARGET_FLAGS_s390		:= s390x-linux-gnu
 CLANG_TARGET_FLAGS_x86		:= x86_64-linux-gnu
+CLANG_TARGET_FLAGS_um		:= $(CLANG_TARGET_FLAGS_$(SUBARCH))
 CLANG_TARGET_FLAGS		:= $(CLANG_TARGET_FLAGS_$(SRCARCH))
 
 ifeq ($(CROSS_COMPILE),)