Merge tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull kernel hardening updates from Kees Cook:

 - Convert flexible array members, fix -Wstringop-overflow warnings, and
   fix KCFI function type mismatches that went ignored by maintainers
   (Gustavo A. R. Silva, Nathan Chancellor, Kees Cook)

 - Remove the remaining side-effect users of ksize() by converting
   dma-buf, btrfs, and coredump to using kmalloc_size_roundup(), add
   more __alloc_size attributes, and introduce full testing of all
   allocator functions. Finally remove the ksize() side-effect so that
   each allocation-aware checker can finally behave without exceptions

 - Introduce oops_limit (default 10,000) and warn_limit (default off) to
   provide greater granularity of control for panic_on_oops and
   panic_on_warn (Jann Horn, Kees Cook)

 - Introduce overflows_type() and castable_to_type() helpers for cleaner
   overflow checking

 - Improve code generation for strscpy() and update str*() kern-doc

 - Convert strscpy and sigphash tests to KUnit, and expand memcpy tests

 - Always use a non-NULL argument for prepare_kernel_cred()

 - Disable structleak plugin in FORTIFY KUnit test (Anders Roxell)

 - Adjust orphan linker section checking to respect CONFIG_WERROR (Xin
   Li)

 - Make sure siginfo is cleared for forced SIGKILL (haifeng.xu)

 - Fix um vs FORTIFY warnings for always-NULL arguments

* tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (31 commits)
  ksmbd: replace one-element arrays with flexible-array members
  hpet: Replace one-element array with flexible-array member
  um: virt-pci: Avoid GCC non-NULL warning
  signal: Initialize the info in ksignal
  lib: fortify_kunit: build without structleak plugin
  panic: Expose "warn_count" to sysfs
  panic: Introduce warn_limit
  panic: Consolidate open-coded panic_on_warn checks
  exit: Allow oops_limit to be disabled
  exit: Expose "oops_count" to sysfs
  exit: Put an upper limit on how often we can oops
  panic: Separate sysctl logic from CONFIG_SMP
  mm/pgtable: Fix multiple -Wstringop-overflow warnings
  mm: Make ksize() a reporting-only function
  kunit/fortify: Validate __alloc_size attribute results
  drm/sti: Fix return type of sti_{dvo,hda,hdmi}_connector_mode_valid()
  drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
  driver core: Add __alloc_size hint to devm allocators
  overflow: Introduce overflows_type() and castable_to_type()
  coredump: Proactively round up to kmalloc bucket size
  ...

10 files changed, 1075 insertions, 343 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1b2bdc02abf4..6831b798152d 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2234,9 +2234,6 @@ config STRING_SELFTEST
 config TEST_STRING_HELPERS
 	tristate "Test functions located in the string_helpers module at runtime"
 
-config TEST_STRSCPY
-	tristate "Test strscpy*() family of functions at runtime"
-
 config TEST_KSTRTOX
 	tristate "Test kstrto*() family of functions at runtime"
 
@@ -2271,15 +2268,6 @@ config TEST_RHASHTABLE
 
 	  If unsure, say N.
 
-config TEST_SIPHASH
-	tristate "Perform selftest on siphash functions"
-	help
-	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
-	  functions on boot (or module load).
-
-	  This is intended to help people writing architecture-specific
-	  optimized versions.  If unsure, say N.
-
 config TEST_IDA
 	tristate "Perform selftest on IDA functions"
 
@@ -2607,6 +2595,22 @@ config HW_BREAKPOINT_KUNIT_TEST
 
 	  If unsure, say N.
 
+config STRSCPY_KUNIT_TEST
+	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+
+config SIPHASH_KUNIT_TEST
+	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
+	  functions on boot (or module load).
+
+	  This is intended to help people writing architecture-specific
+	  optimized versions.  If unsure, say N.
+
 config TEST_UDELAY
 	tristate "udelay test driver"
 	help
diff --git a/lib/Makefile b/lib/Makefile
index 59bd7c2f793a..4d9461bfea42 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -62,7 +62,6 @@ obj-$(CONFIG_TEST_BITOPS) += test_bitops.o
 CFLAGS_test_bitops.o += -Werror
 obj-$(CONFIG_CPUMASK_KUNIT_TEST) += cpumask_kunit.o
 obj-$(CONFIG_TEST_SYSCTL) += test_sysctl.o
-obj-$(CONFIG_TEST_SIPHASH) += test_siphash.o
 obj-$(CONFIG_HASH_KUNIT_TEST) += test_hash.o
 obj-$(CONFIG_TEST_IDA) += test_ida.o
 obj-$(CONFIG_TEST_UBSAN) += test_ubsan.o
@@ -82,7 +81,6 @@ obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o
 obj-$(CONFIG_TEST_PRINTF) += test_printf.o
 obj-$(CONFIG_TEST_SCANF) += test_scanf.o
 obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
-obj-$(CONFIG_TEST_STRSCPY) += test_strscpy.o
 obj-$(CONFIG_TEST_UUID) += test_uuid.o
 obj-$(CONFIG_TEST_XARRAY) += test_xarray.o
 obj-$(CONFIG_TEST_MAPLE_TREE) += test_maple_tree.o
@@ -377,10 +375,15 @@ obj-$(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_IS_SIGNED_TYPE_KUNIT_TEST) += is_signed_type_kunit.o
+CFLAGS_overflow_kunit.o = $(call cc-disable-warning, tautological-constant-out-of-range-compare)
 obj-$(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
+CFLAGS_fortify_kunit.o += $(call cc-disable-warning, unsequenced)
+CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN)
 obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
+obj-$(CONFIG_STRSCPY_KUNIT_TEST) += strscpy_kunit.o
+obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o
 
 obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
 
diff --git a/lib/fortify_kunit.c b/lib/fortify_kunit.c
index 409af07f340a..c8c33cbaae9e 100644
--- a/lib/fortify_kunit.c
+++ b/lib/fortify_kunit.c
@@ -16,7 +16,10 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <kunit/test.h>
+#include <linux/device.h>
+#include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/vmalloc.h>
 
 static const char array_of_10[] = "this is 10";
 static const char *ptr_of_11 = "this is 11!";
@@ -60,9 +63,261 @@ static void control_flow_split_test(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, want_minus_one(pick), SIZE_MAX);
 }
 
+#define KUNIT_EXPECT_BOS(test, p, expected, name)			\
+	KUNIT_EXPECT_EQ_MSG(test, __builtin_object_size(p, 1),		\
+		expected,						\
+		"__alloc_size() not working with __bos on " name "\n")
+
+#if !__has_builtin(__builtin_dynamic_object_size)
+#define KUNIT_EXPECT_BDOS(test, p, expected, name)			\
+	/* Silence "unused variable 'expected'" warning. */		\
+	KUNIT_EXPECT_EQ(test, expected, expected)
+#else
+#define KUNIT_EXPECT_BDOS(test, p, expected, name)			\
+	KUNIT_EXPECT_EQ_MSG(test, __builtin_dynamic_object_size(p, 1),	\
+		expected,						\
+		"__alloc_size() not working with __bdos on " name "\n")
+#endif
+
+/* If the execpted size is a constant value, __bos can see it. */
+#define check_const(_expected, alloc, free)		do {		\
+	size_t expected = (_expected);					\
+	void *p = alloc;						\
+	KUNIT_EXPECT_TRUE_MSG(test, p != NULL, #alloc " failed?!\n");	\
+	KUNIT_EXPECT_BOS(test, p, expected, #alloc);			\
+	KUNIT_EXPECT_BDOS(test, p, expected, #alloc);			\
+	free;								\
+} while (0)
+
+/* If the execpted size is NOT a constant value, __bos CANNOT see it. */
+#define check_dynamic(_expected, alloc, free)		do {		\
+	size_t expected = (_expected);					\
+	void *p = alloc;						\
+	KUNIT_EXPECT_TRUE_MSG(test, p != NULL, #alloc " failed?!\n");	\
+	KUNIT_EXPECT_BOS(test, p, SIZE_MAX, #alloc);			\
+	KUNIT_EXPECT_BDOS(test, p, expected, #alloc);			\
+	free;								\
+} while (0)
+
+/* Assortment of constant-value kinda-edge cases. */
+#define CONST_TEST_BODY(TEST_alloc)	do {				\
+	/* Special-case vmalloc()-family to skip 0-sized allocs. */	\
+	if (strcmp(#TEST_alloc, "TEST_vmalloc") != 0)			\
+		TEST_alloc(check_const, 0, 0);				\
+	TEST_alloc(check_const, 1, 1);					\
+	TEST_alloc(check_const, 128, 128);				\
+	TEST_alloc(check_const, 1023, 1023);				\
+	TEST_alloc(check_const, 1025, 1025);				\
+	TEST_alloc(check_const, 4096, 4096);				\
+	TEST_alloc(check_const, 4097, 4097);				\
+} while (0)
+
+static volatile size_t zero_size;
+static volatile size_t unknown_size = 50;
+
+#if !__has_builtin(__builtin_dynamic_object_size)
+#define DYNAMIC_TEST_BODY(TEST_alloc)					\
+	kunit_skip(test, "Compiler is missing __builtin_dynamic_object_size() support\n")
+#else
+#define DYNAMIC_TEST_BODY(TEST_alloc)	do {				\
+	size_t size = unknown_size;					\
+									\
+	/*								\
+	 * Expected size is "size" in each test, before it is then	\
+	 * internally incremented in each test.	Requires we disable	\
+	 * -Wunsequenced.						\
+	 */								\
+	TEST_alloc(check_dynamic, size, size++);			\
+	/* Make sure incrementing actually happened. */			\
+	KUNIT_EXPECT_NE(test, size, unknown_size);			\
+} while (0)
+#endif
+
+#define DEFINE_ALLOC_SIZE_TEST_PAIR(allocator)				\
+static void alloc_size_##allocator##_const_test(struct kunit *test)	\
+{									\
+	CONST_TEST_BODY(TEST_##allocator);				\
+}									\
+static void alloc_size_##allocator##_dynamic_test(struct kunit *test)	\
+{									\
+	DYNAMIC_TEST_BODY(TEST_##allocator);				\
+}
+
+#define TEST_kmalloc(checker, expected_size, alloc_size)	do {	\
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
+	void *orig;							\
+	size_t len;							\
+									\
+	checker(expected_size, kmalloc(alloc_size, gfp),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		kmalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+	checker(expected_size, kzalloc(alloc_size, gfp),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		kzalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+	checker(expected_size, kcalloc(1, alloc_size, gfp),		\
+		kfree(p));						\
+	checker(expected_size, kcalloc(alloc_size, 1, gfp),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		kcalloc_node(1, alloc_size, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		kcalloc_node(alloc_size, 1, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+	checker(expected_size, kmalloc_array(1, alloc_size, gfp),	\
+		kfree(p));						\
+	checker(expected_size, kmalloc_array(alloc_size, 1, gfp),	\
+		kfree(p));						\
+	checker(expected_size,						\
+		kmalloc_array_node(1, alloc_size, gfp, NUMA_NO_NODE),	\
+		kfree(p));						\
+	checker(expected_size,						\
+		kmalloc_array_node(alloc_size, 1, gfp, NUMA_NO_NODE),	\
+		kfree(p));						\
+	checker(expected_size, __kmalloc(alloc_size, gfp),		\
+		kfree(p));						\
+	checker(expected_size,						\
+		__kmalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
+		kfree(p));						\
+									\
+	orig = kmalloc(alloc_size, gfp);				\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker((expected_size) * 2,					\
+		krealloc(orig, (alloc_size) * 2, gfp),			\
+		kfree(p));						\
+	orig = kmalloc(alloc_size, gfp);				\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker((expected_size) * 2,					\
+		krealloc_array(orig, 1, (alloc_size) * 2, gfp),		\
+		kfree(p));						\
+	orig = kmalloc(alloc_size, gfp);				\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker((expected_size) * 2,					\
+		krealloc_array(orig, (alloc_size) * 2, 1, gfp),		\
+		kfree(p));						\
+									\
+	len = 11;							\
+	/* Using memdup() with fixed size, so force unknown length. */	\
+	if (!__builtin_constant_p(expected_size))			\
+		len += zero_size;					\
+	checker(len, kmemdup("hello there", len, gfp), kfree(p));	\
+} while (0)
+DEFINE_ALLOC_SIZE_TEST_PAIR(kmalloc)
+
+/* Sizes are in pages, not bytes. */
+#define TEST_vmalloc(checker, expected_pages, alloc_pages)	do {	\
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
+	checker((expected_pages) * PAGE_SIZE,				\
+		vmalloc((alloc_pages) * PAGE_SIZE),	   vfree(p));	\
+	checker((expected_pages) * PAGE_SIZE,				\
+		vzalloc((alloc_pages) * PAGE_SIZE),	   vfree(p));	\
+	checker((expected_pages) * PAGE_SIZE,				\
+		__vmalloc((alloc_pages) * PAGE_SIZE, gfp), vfree(p));	\
+} while (0)
+DEFINE_ALLOC_SIZE_TEST_PAIR(vmalloc)
+
+/* Sizes are in pages (and open-coded for side-effects), not bytes. */
+#define TEST_kvmalloc(checker, expected_pages, alloc_pages)	do {	\
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
+	size_t prev_size;						\
+	void *orig;							\
+									\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvmalloc((alloc_pages) * PAGE_SIZE, gfp),		\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvmalloc_node((alloc_pages) * PAGE_SIZE, gfp, NUMA_NO_NODE), \
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvzalloc((alloc_pages) * PAGE_SIZE, gfp),		\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvzalloc_node((alloc_pages) * PAGE_SIZE, gfp, NUMA_NO_NODE), \
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvcalloc(1, (alloc_pages) * PAGE_SIZE, gfp),		\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvcalloc((alloc_pages) * PAGE_SIZE, 1, gfp),		\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvmalloc_array(1, (alloc_pages) * PAGE_SIZE, gfp),	\
+		vfree(p));						\
+	checker((expected_pages) * PAGE_SIZE,				\
+		kvmalloc_array((alloc_pages) * PAGE_SIZE, 1, gfp),	\
+		vfree(p));						\
+									\
+	prev_size = (expected_pages) * PAGE_SIZE;			\
+	orig = kvmalloc(prev_size, gfp);				\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker(((expected_pages) * PAGE_SIZE) * 2,			\
+		kvrealloc(orig, prev_size,				\
+			  ((alloc_pages) * PAGE_SIZE) * 2, gfp),	\
+		kvfree(p));						\
+} while (0)
+DEFINE_ALLOC_SIZE_TEST_PAIR(kvmalloc)
+
+#define TEST_devm_kmalloc(checker, expected_size, alloc_size)	do {	\
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
+	const char dev_name[] = "fortify-test";				\
+	struct device *dev;						\
+	void *orig;							\
+	size_t len;							\
+									\
+	/* Create dummy device for devm_kmalloc()-family tests. */	\
+	dev = root_device_register(dev_name);				\
+	KUNIT_ASSERT_FALSE_MSG(test, IS_ERR(dev),			\
+			       "Cannot register test device\n");	\
+									\
+	checker(expected_size, devm_kmalloc(dev, alloc_size, gfp),	\
+		devm_kfree(dev, p));					\
+	checker(expected_size, devm_kzalloc(dev, alloc_size, gfp),	\
+		devm_kfree(dev, p));					\
+	checker(expected_size,						\
+		devm_kmalloc_array(dev, 1, alloc_size, gfp),		\
+		devm_kfree(dev, p));					\
+	checker(expected_size,						\
+		devm_kmalloc_array(dev, alloc_size, 1, gfp),		\
+		devm_kfree(dev, p));					\
+	checker(expected_size,						\
+		devm_kcalloc(dev, 1, alloc_size, gfp),			\
+		devm_kfree(dev, p));					\
+	checker(expected_size,						\
+		devm_kcalloc(dev, alloc_size, 1, gfp),			\
+		devm_kfree(dev, p));					\
+									\
+	orig = devm_kmalloc(dev, alloc_size, gfp);			\
+	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
+	checker((expected_size) * 2,					\
+		devm_krealloc(dev, orig, (alloc_size) * 2, gfp),	\
+		devm_kfree(dev, p));					\
+									\
+	len = 4;							\
+	/* Using memdup() with fixed size, so force unknown length. */	\
+	if (!__builtin_constant_p(expected_size))			\
+		len += zero_size;					\
+	checker(len, devm_kmemdup(dev, "Ohai", len, gfp),		\
+		devm_kfree(dev, p));					\
+									\
+	device_unregister(dev);						\
+} while (0)
+DEFINE_ALLOC_SIZE_TEST_PAIR(devm_kmalloc)
+
 static struct kunit_case fortify_test_cases[] = {
 	KUNIT_CASE(known_sizes_test),
 	KUNIT_CASE(control_flow_split_test),
+	KUNIT_CASE(alloc_size_kmalloc_const_test),
+	KUNIT_CASE(alloc_size_kmalloc_dynamic_test),
+	KUNIT_CASE(alloc_size_vmalloc_const_test),
+	KUNIT_CASE(alloc_size_vmalloc_dynamic_test),
+	KUNIT_CASE(alloc_size_kvmalloc_const_test),
+	KUNIT_CASE(alloc_size_kvmalloc_dynamic_test),
+	KUNIT_CASE(alloc_size_devm_kmalloc_const_test),
+	KUNIT_CASE(alloc_size_devm_kmalloc_dynamic_test),
 	{}
 };
 
diff --git a/lib/memcpy_kunit.c b/lib/memcpy_kunit.c
index 7513e6d5dc90..89128551448d 100644
--- a/lib/memcpy_kunit.c
+++ b/lib/memcpy_kunit.c
@@ -292,6 +292,208 @@ static void memset_test(struct kunit *test)
 #undef TEST_OP
 }
 
+static u8 large_src[1024];
+static u8 large_dst[2048];
+static const u8 large_zero[2048];
+
+static void set_random_nonzero(struct kunit *test, u8 *byte)
+{
+	int failed_rng = 0;
+
+	while (*byte == 0) {
+		get_random_bytes(byte, 1);
+		KUNIT_ASSERT_LT_MSG(test, failed_rng++, 100,
+				    "Is the RNG broken?");
+	}
+}
+
+static void init_large(struct kunit *test)
+{
+
+	/* Get many bit patterns. */
+	get_random_bytes(large_src, ARRAY_SIZE(large_src));
+
+	/* Make sure we have non-zero edges. */
+	set_random_nonzero(test, &large_src[0]);
+	set_random_nonzero(test, &large_src[ARRAY_SIZE(large_src) - 1]);
+
+	/* Explicitly zero the entire destination. */
+	memset(large_dst, 0, ARRAY_SIZE(large_dst));
+}
+
+/*
+ * Instead of an indirect function call for "copy" or a giant macro,
+ * use a bool to pick memcpy or memmove.
+ */
+static void copy_large_test(struct kunit *test, bool use_memmove)
+{
+	init_large(test);
+
+	/* Copy a growing number of non-overlapping bytes ... */
+	for (int bytes = 1; bytes <= ARRAY_SIZE(large_src); bytes++) {
+		/* Over a shifting destination window ... */
+		for (int offset = 0; offset < ARRAY_SIZE(large_src); offset++) {
+			int right_zero_pos = offset + bytes;
+			int right_zero_size = ARRAY_SIZE(large_dst) - right_zero_pos;
+
+			/* Copy! */
+			if (use_memmove)
+				memmove(large_dst + offset, large_src, bytes);
+			else
+				memcpy(large_dst + offset, large_src, bytes);
+
+			/* Did we touch anything before the copy area? */
+			KUNIT_ASSERT_EQ_MSG(test,
+				memcmp(large_dst, large_zero, offset), 0,
+				"with size %d at offset %d", bytes, offset);
+			/* Did we touch anything after the copy area? */
+			KUNIT_ASSERT_EQ_MSG(test,
+				memcmp(&large_dst[right_zero_pos], large_zero, right_zero_size), 0,
+				"with size %d at offset %d", bytes, offset);
+
+			/* Are we byte-for-byte exact across the copy? */
+			KUNIT_ASSERT_EQ_MSG(test,
+				memcmp(large_dst + offset, large_src, bytes), 0,
+				"with size %d at offset %d", bytes, offset);
+
+			/* Zero out what we copied for the next cycle. */
+			memset(large_dst + offset, 0, bytes);
+		}
+		/* Avoid stall warnings if this loop gets slow. */
+		cond_resched();
+	}
+}
+
+static void memcpy_large_test(struct kunit *test)
+{
+	copy_large_test(test, false);
+}
+
+static void memmove_large_test(struct kunit *test)
+{
+	copy_large_test(test, true);
+}
+
+/*
+ * On the assumption that boundary conditions are going to be the most
+ * sensitive, instead of taking a full step (inc) each iteration,
+ * take single index steps for at least the first "inc"-many indexes
+ * from the "start" and at least the last "inc"-many indexes before
+ * the "end". When in the middle, take full "inc"-wide steps. For
+ * example, calling next_step(idx, 1, 15, 3) with idx starting at 0
+ * would see the following pattern: 1 2 3 4 7 10 11 12 13 14 15.
+ */
+static int next_step(int idx, int start, int end, int inc)
+{
+	start += inc;
+	end -= inc;
+
+	if (idx < start || idx + inc > end)
+		inc = 1;
+	return idx + inc;
+}
+
+static void inner_loop(struct kunit *test, int bytes, int d_off, int s_off)
+{
+	int left_zero_pos, left_zero_size;
+	int right_zero_pos, right_zero_size;
+	int src_pos, src_orig_pos, src_size;
+	int pos;
+
+	/* Place the source in the destination buffer. */
+	memcpy(&large_dst[s_off], large_src, bytes);
+
+	/* Copy to destination offset. */
+	memmove(&large_dst[d_off], &large_dst[s_off], bytes);
+
+	/* Make sure destination entirely matches. */
+	KUNIT_ASSERT_EQ_MSG(test, memcmp(&large_dst[d_off], large_src, bytes), 0,
+		"with size %d at src offset %d and dest offset %d",
+		bytes, s_off, d_off);
+
+	/* Calculate the expected zero spans. */
+	if (s_off < d_off) {
+		left_zero_pos = 0;
+		left_zero_size = s_off;
+
+		right_zero_pos = d_off + bytes;
+		right_zero_size = ARRAY_SIZE(large_dst) - right_zero_pos;
+
+		src_pos = s_off;
+		src_orig_pos = 0;
+		src_size = d_off - s_off;
+	} else {
+		left_zero_pos = 0;
+		left_zero_size = d_off;
+
+		right_zero_pos = s_off + bytes;
+		right_zero_size = ARRAY_SIZE(large_dst) - right_zero_pos;
+
+		src_pos = d_off + bytes;
+		src_orig_pos = src_pos - s_off;
+		src_size = right_zero_pos - src_pos;
+	}
+
+	/* Check non-overlapping source is unchanged.*/
+	KUNIT_ASSERT_EQ_MSG(test,
+		memcmp(&large_dst[src_pos], &large_src[src_orig_pos], src_size), 0,
+		"with size %d at src offset %d and dest offset %d",
+		bytes, s_off, d_off);
+
+	/* Check leading buffer contents are zero. */
+	KUNIT_ASSERT_EQ_MSG(test,
+		memcmp(&large_dst[left_zero_pos], large_zero, left_zero_size), 0,
+		"with size %d at src offset %d and dest offset %d",
+		bytes, s_off, d_off);
+	/* Check trailing buffer contents are zero. */
+	KUNIT_ASSERT_EQ_MSG(test,
+		memcmp(&large_dst[right_zero_pos], large_zero, right_zero_size), 0,
+		"with size %d at src offset %d and dest offset %d",
+		bytes, s_off, d_off);
+
+	/* Zero out everything not already zeroed.*/
+	pos = left_zero_pos + left_zero_size;
+	memset(&large_dst[pos], 0, right_zero_pos - pos);
+}
+
+static void memmove_overlap_test(struct kunit *test)
+{
+	/*
+	 * Running all possible offset and overlap combinations takes a
+	 * very long time. Instead, only check up to 128 bytes offset
+	 * into the destination buffer (which should result in crossing
+	 * cachelines), with a step size of 1 through 7 to try to skip some
+	 * redundancy.
+	 */
+	static const int offset_max = 128; /* less than ARRAY_SIZE(large_src); */
+	static const int bytes_step = 7;
+	static const int window_step = 7;
+
+	static const int bytes_start = 1;
+	static const int bytes_end = ARRAY_SIZE(large_src) + 1;
+
+	init_large(test);
+
+	/* Copy a growing number of overlapping bytes ... */
+	for (int bytes = bytes_start; bytes < bytes_end;
+	     bytes = next_step(bytes, bytes_start, bytes_end, bytes_step)) {
+
+		/* Over a shifting destination window ... */
+		for (int d_off = 0; d_off < offset_max; d_off++) {
+			int s_start = max(d_off - bytes, 0);
+			int s_end = min_t(int, d_off + bytes, ARRAY_SIZE(large_src));
+
+			/* Over a shifting source window ... */
+			for (int s_off = s_start; s_off < s_end;
+			     s_off = next_step(s_off, s_start, s_end, window_step))
+				inner_loop(test, bytes, d_off, s_off);
+
+			/* Avoid stall warnings. */
+			cond_resched();
+		}
+	}
+}
+
 static void strtomem_test(struct kunit *test)
 {
 	static const char input[sizeof(unsigned long)] = "hi";
@@ -347,7 +549,10 @@ static void strtomem_test(struct kunit *test)
 static struct kunit_case memcpy_test_cases[] = {
 	KUNIT_CASE(memset_test),
 	KUNIT_CASE(memcpy_test),
+	KUNIT_CASE(memcpy_large_test),
 	KUNIT_CASE(memmove_test),
+	KUNIT_CASE(memmove_large_test),
+	KUNIT_CASE(memmove_overlap_test),
 	KUNIT_CASE(strtomem_test),
 	{}
 };
diff --git a/lib/overflow_kunit.c b/lib/overflow_kunit.c
index b8556a2e7bb1..dcd3ba102db6 100644
--- a/lib/overflow_kunit.c
+++ b/lib/overflow_kunit.c
@@ -736,6 +736,384 @@ static void overflow_size_helpers_test(struct kunit *test)
 #undef check_one_size_helper
 }
 
+static void overflows_type_test(struct kunit *test)
+{
+	int count = 0;
+	unsigned int var;
+
+#define __TEST_OVERFLOWS_TYPE(func, arg1, arg2, of)	do {		\
+	bool __of = func(arg1, arg2);					\
+	KUNIT_EXPECT_EQ_MSG(test, __of, of,				\
+		"expected " #func "(" #arg1 ", " #arg2 " to%s overflow\n",\
+		of ? "" : " not");					\
+	count++;							\
+} while (0)
+
+/* Args are: first type, second type, value, overflow expected */
+#define TEST_OVERFLOWS_TYPE(__t1, __t2, v, of) do {			\
+	__t1 t1 = (v);							\
+	__t2 t2;							\
+	__TEST_OVERFLOWS_TYPE(__overflows_type, t1, t2, of);		\
+	__TEST_OVERFLOWS_TYPE(__overflows_type, t1, __t2, of);		\
+	__TEST_OVERFLOWS_TYPE(__overflows_type_constexpr, t1, t2, of);	\
+	__TEST_OVERFLOWS_TYPE(__overflows_type_constexpr, t1, __t2, of);\
+} while (0)
+
+	TEST_OVERFLOWS_TYPE(u8, u8, U8_MAX, false);
+	TEST_OVERFLOWS_TYPE(u8, u16, U8_MAX, false);
+	TEST_OVERFLOWS_TYPE(u8, s8, U8_MAX, true);
+	TEST_OVERFLOWS_TYPE(u8, s8, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(u8, s8, (u8)S8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u8, s16, U8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s8, u8, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s8, u8, -1, true);
+	TEST_OVERFLOWS_TYPE(s8, u8, S8_MIN, true);
+	TEST_OVERFLOWS_TYPE(s8, u16, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s8, u16, -1, true);
+	TEST_OVERFLOWS_TYPE(s8, u16, S8_MIN, true);
+	TEST_OVERFLOWS_TYPE(s8, u32, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s8, u32, -1, true);
+	TEST_OVERFLOWS_TYPE(s8, u32, S8_MIN, true);
+#if BITS_PER_LONG == 64
+	TEST_OVERFLOWS_TYPE(s8, u64, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s8, u64, -1, true);
+	TEST_OVERFLOWS_TYPE(s8, u64, S8_MIN, true);
+#endif
+	TEST_OVERFLOWS_TYPE(s8, s8, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s8, s8, S8_MIN, false);
+	TEST_OVERFLOWS_TYPE(s8, s16, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s8, s16, S8_MIN, false);
+	TEST_OVERFLOWS_TYPE(u16, u8, U8_MAX, false);
+	TEST_OVERFLOWS_TYPE(u16, u8, (u16)U8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u16, u8, U16_MAX, true);
+	TEST_OVERFLOWS_TYPE(u16, s8, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(u16, s8, (u16)S8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u16, s8, U16_MAX, true);
+	TEST_OVERFLOWS_TYPE(u16, s16, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(u16, s16, (u16)S16_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u16, s16, U16_MAX, true);
+	TEST_OVERFLOWS_TYPE(u16, u32, U16_MAX, false);
+	TEST_OVERFLOWS_TYPE(u16, s32, U16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s16, u8, U8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s16, u8, (s16)U8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s16, u8, -1, true);
+	TEST_OVERFLOWS_TYPE(s16, u8, S16_MIN, true);
+	TEST_OVERFLOWS_TYPE(s16, u16, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s16, u16, -1, true);
+	TEST_OVERFLOWS_TYPE(s16, u16, S16_MIN, true);
+	TEST_OVERFLOWS_TYPE(s16, u32, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s16, u32, -1, true);
+	TEST_OVERFLOWS_TYPE(s16, u32, S16_MIN, true);
+#if BITS_PER_LONG == 64
+	TEST_OVERFLOWS_TYPE(s16, u64, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s16, u64, -1, true);
+	TEST_OVERFLOWS_TYPE(s16, u64, S16_MIN, true);
+#endif
+	TEST_OVERFLOWS_TYPE(s16, s8, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s16, s8, S8_MIN, false);
+	TEST_OVERFLOWS_TYPE(s16, s8, (s16)S8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s16, s8, (s16)S8_MIN - 1, true);
+	TEST_OVERFLOWS_TYPE(s16, s8, S16_MAX, true);
+	TEST_OVERFLOWS_TYPE(s16, s8, S16_MIN, true);
+	TEST_OVERFLOWS_TYPE(s16, s16, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s16, s16, S16_MIN, false);
+	TEST_OVERFLOWS_TYPE(s16, s32, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s16, s32, S16_MIN, false);
+	TEST_OVERFLOWS_TYPE(u32, u8, U8_MAX, false);
+	TEST_OVERFLOWS_TYPE(u32, u8, (u32)U8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u32, u8, U32_MAX, true);
+	TEST_OVERFLOWS_TYPE(u32, s8, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(u32, s8, (u32)S8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u32, s8, U32_MAX, true);
+	TEST_OVERFLOWS_TYPE(u32, u16, U16_MAX, false);
+	TEST_OVERFLOWS_TYPE(u32, u16, U16_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u32, u16, U32_MAX, true);
+	TEST_OVERFLOWS_TYPE(u32, s16, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(u32, s16, (u32)S16_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u32, s16, U32_MAX, true);
+	TEST_OVERFLOWS_TYPE(u32, u32, U32_MAX, false);
+	TEST_OVERFLOWS_TYPE(u32, s32, S32_MAX, false);
+	TEST_OVERFLOWS_TYPE(u32, s32, U32_MAX, true);
+	TEST_OVERFLOWS_TYPE(u32, s32, (u32)S32_MAX + 1, true);
+#if BITS_PER_LONG == 64
+	TEST_OVERFLOWS_TYPE(u32, u64, U32_MAX, false);
+	TEST_OVERFLOWS_TYPE(u32, s64, U32_MAX, false);
+#endif
+	TEST_OVERFLOWS_TYPE(s32, u8, U8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s32, u8, (s32)U8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s32, u16, S32_MAX, true);
+	TEST_OVERFLOWS_TYPE(s32, u8, -1, true);
+	TEST_OVERFLOWS_TYPE(s32, u8, S32_MIN, true);
+	TEST_OVERFLOWS_TYPE(s32, u16, U16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s32, u16, (s32)U16_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s32, u16, S32_MAX, true);
+	TEST_OVERFLOWS_TYPE(s32, u16, -1, true);
+	TEST_OVERFLOWS_TYPE(s32, u16, S32_MIN, true);
+	TEST_OVERFLOWS_TYPE(s32, u32, S32_MAX, false);
+	TEST_OVERFLOWS_TYPE(s32, u32, -1, true);
+	TEST_OVERFLOWS_TYPE(s32, u32, S32_MIN, true);
+#if BITS_PER_LONG == 64
+	TEST_OVERFLOWS_TYPE(s32, u64, S32_MAX, false);
+	TEST_OVERFLOWS_TYPE(s32, u64, -1, true);
+	TEST_OVERFLOWS_TYPE(s32, u64, S32_MIN, true);
+#endif
+	TEST_OVERFLOWS_TYPE(s32, s8, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s32, s8, S8_MIN, false);
+	TEST_OVERFLOWS_TYPE(s32, s8, (s32)S8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s32, s8, (s32)S8_MIN - 1, true);
+	TEST_OVERFLOWS_TYPE(s32, s8, S32_MAX, true);
+	TEST_OVERFLOWS_TYPE(s32, s8, S32_MIN, true);
+	TEST_OVERFLOWS_TYPE(s32, s16, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s32, s16, S16_MIN, false);
+	TEST_OVERFLOWS_TYPE(s32, s16, (s32)S16_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s32, s16, (s32)S16_MIN - 1, true);
+	TEST_OVERFLOWS_TYPE(s32, s16, S32_MAX, true);
+	TEST_OVERFLOWS_TYPE(s32, s16, S32_MIN, true);
+	TEST_OVERFLOWS_TYPE(s32, s32, S32_MAX, false);
+	TEST_OVERFLOWS_TYPE(s32, s32, S32_MIN, false);
+#if BITS_PER_LONG == 64
+	TEST_OVERFLOWS_TYPE(s32, s64, S32_MAX, false);
+	TEST_OVERFLOWS_TYPE(s32, s64, S32_MIN, false);
+	TEST_OVERFLOWS_TYPE(u64, u8, U64_MAX, true);
+	TEST_OVERFLOWS_TYPE(u64, u8, U8_MAX, false);
+	TEST_OVERFLOWS_TYPE(u64, u8, (u64)U8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u64, u16, U64_MAX, true);
+	TEST_OVERFLOWS_TYPE(u64, u16, U16_MAX, false);
+	TEST_OVERFLOWS_TYPE(u64, u16, (u64)U16_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u64, u32, U64_MAX, true);
+	TEST_OVERFLOWS_TYPE(u64, u32, U32_MAX, false);
+	TEST_OVERFLOWS_TYPE(u64, u32, (u64)U32_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u64, u64, U64_MAX, false);
+	TEST_OVERFLOWS_TYPE(u64, s8, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(u64, s8, (u64)S8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u64, s8, U64_MAX, true);
+	TEST_OVERFLOWS_TYPE(u64, s16, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(u64, s16, (u64)S16_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u64, s16, U64_MAX, true);
+	TEST_OVERFLOWS_TYPE(u64, s32, S32_MAX, false);
+	TEST_OVERFLOWS_TYPE(u64, s32, (u64)S32_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(u64, s32, U64_MAX, true);
+	TEST_OVERFLOWS_TYPE(u64, s64, S64_MAX, false);
+	TEST_OVERFLOWS_TYPE(u64, s64, U64_MAX, true);
+	TEST_OVERFLOWS_TYPE(u64, s64, (u64)S64_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s64, u8, S64_MAX, true);
+	TEST_OVERFLOWS_TYPE(s64, u8, S64_MIN, true);
+	TEST_OVERFLOWS_TYPE(s64, u8, -1, true);
+	TEST_OVERFLOWS_TYPE(s64, u8, U8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s64, u8, (s64)U8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s64, u16, S64_MAX, true);
+	TEST_OVERFLOWS_TYPE(s64, u16, S64_MIN, true);
+	TEST_OVERFLOWS_TYPE(s64, u16, -1, true);
+	TEST_OVERFLOWS_TYPE(s64, u16, U16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s64, u16, (s64)U16_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s64, u32, S64_MAX, true);
+	TEST_OVERFLOWS_TYPE(s64, u32, S64_MIN, true);
+	TEST_OVERFLOWS_TYPE(s64, u32, -1, true);
+	TEST_OVERFLOWS_TYPE(s64, u32, U32_MAX, false);
+	TEST_OVERFLOWS_TYPE(s64, u32, (s64)U32_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s64, u64, S64_MAX, false);
+	TEST_OVERFLOWS_TYPE(s64, u64, S64_MIN, true);
+	TEST_OVERFLOWS_TYPE(s64, u64, -1, true);
+	TEST_OVERFLOWS_TYPE(s64, s8, S8_MAX, false);
+	TEST_OVERFLOWS_TYPE(s64, s8, S8_MIN, false);
+	TEST_OVERFLOWS_TYPE(s64, s8, (s64)S8_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s64, s8, (s64)S8_MIN - 1, true);
+	TEST_OVERFLOWS_TYPE(s64, s8, S64_MAX, true);
+	TEST_OVERFLOWS_TYPE(s64, s16, S16_MAX, false);
+	TEST_OVERFLOWS_TYPE(s64, s16, S16_MIN, false);
+	TEST_OVERFLOWS_TYPE(s64, s16, (s64)S16_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s64, s16, (s64)S16_MIN - 1, true);
+	TEST_OVERFLOWS_TYPE(s64, s16, S64_MAX, true);
+	TEST_OVERFLOWS_TYPE(s64, s32, S32_MAX, false);
+	TEST_OVERFLOWS_TYPE(s64, s32, S32_MIN, false);
+	TEST_OVERFLOWS_TYPE(s64, s32, (s64)S32_MAX + 1, true);
+	TEST_OVERFLOWS_TYPE(s64, s32, (s64)S32_MIN - 1, true);
+	TEST_OVERFLOWS_TYPE(s64, s32, S64_MAX, true);
+	TEST_OVERFLOWS_TYPE(s64, s64, S64_MAX, false);
+	TEST_OVERFLOWS_TYPE(s64, s64, S64_MIN, false);
+#endif
+
+	/* Check for macro side-effects. */
+	var = INT_MAX - 1;
+	__TEST_OVERFLOWS_TYPE(__overflows_type, var++, int, false);
+	__TEST_OVERFLOWS_TYPE(__overflows_type, var++, int, false);
+	__TEST_OVERFLOWS_TYPE(__overflows_type, var++, int, true);
+	var = INT_MAX - 1;
+	__TEST_OVERFLOWS_TYPE(overflows_type, var++, int, false);
+	__TEST_OVERFLOWS_TYPE(overflows_type, var++, int, false);
+	__TEST_OVERFLOWS_TYPE(overflows_type, var++, int, true);
+
+	kunit_info(test, "%d overflows_type() tests finished\n", count);
+#undef TEST_OVERFLOWS_TYPE
+#undef __TEST_OVERFLOWS_TYPE
+}
+
+static void same_type_test(struct kunit *test)
+{
+	int count = 0;
+	int var;
+
+#define TEST_SAME_TYPE(t1, t2, same)			do {	\
+	typeof(t1) __t1h = type_max(t1);			\
+	typeof(t1) __t1l = type_min(t1);			\
+	typeof(t2) __t2h = type_max(t2);			\
+	typeof(t2) __t2l = type_min(t2);			\
+	KUNIT_EXPECT_EQ(test, true, __same_type(t1, __t1h));	\
+	KUNIT_EXPECT_EQ(test, true, __same_type(t1, __t1l));	\
+	KUNIT_EXPECT_EQ(test, true, __same_type(__t1h, t1));	\
+	KUNIT_EXPECT_EQ(test, true, __same_type(__t1l, t1));	\
+	KUNIT_EXPECT_EQ(test, true, __same_type(t2, __t2h));	\
+	KUNIT_EXPECT_EQ(test, true, __same_type(t2, __t2l));	\
+	KUNIT_EXPECT_EQ(test, true, __same_type(__t2h, t2));	\
+	KUNIT_EXPECT_EQ(test, true, __same_type(__t2l, t2));	\
+	KUNIT_EXPECT_EQ(test, same, __same_type(t1, t2));	\
+	KUNIT_EXPECT_EQ(test, same, __same_type(t2, __t1h));	\
+	KUNIT_EXPECT_EQ(test, same, __same_type(t2, __t1l));	\
+	KUNIT_EXPECT_EQ(test, same, __same_type(__t1h, t2));	\
+	KUNIT_EXPECT_EQ(test, same, __same_type(__t1l, t2));	\
+	KUNIT_EXPECT_EQ(test, same, __same_type(t1, __t2h));	\
+	KUNIT_EXPECT_EQ(test, same, __same_type(t1, __t2l));	\
+	KUNIT_EXPECT_EQ(test, same, __same_type(__t2h, t1));	\
+	KUNIT_EXPECT_EQ(test, same, __same_type(__t2l, t1));	\
+} while (0)
+
+#if BITS_PER_LONG == 64
+# define TEST_SAME_TYPE64(base, t, m)	TEST_SAME_TYPE(base, t, m)
+#else
+# define TEST_SAME_TYPE64(base, t, m)	do { } while (0)
+#endif
+
+#define TEST_TYPE_SETS(base, mu8, mu16, mu32, ms8, ms16, ms32, mu64, ms64) \
+do {									\
+	TEST_SAME_TYPE(base,  u8,  mu8);				\
+	TEST_SAME_TYPE(base, u16, mu16);				\
+	TEST_SAME_TYPE(base, u32, mu32);				\
+	TEST_SAME_TYPE(base,  s8,  ms8);				\
+	TEST_SAME_TYPE(base, s16, ms16);				\
+	TEST_SAME_TYPE(base, s32, ms32);				\
+	TEST_SAME_TYPE64(base, u64, mu64);				\
+	TEST_SAME_TYPE64(base, s64, ms64);				\
+} while (0)
+
+	TEST_TYPE_SETS(u8,   true, false, false, false, false, false, false, false);
+	TEST_TYPE_SETS(u16, false,  true, false, false, false, false, false, false);
+	TEST_TYPE_SETS(u32, false, false,  true, false, false, false, false, false);
+	TEST_TYPE_SETS(s8,  false, false, false,  true, false, false, false, false);
+	TEST_TYPE_SETS(s16, false, false, false, false,  true, false, false, false);
+	TEST_TYPE_SETS(s32, false, false, false, false, false,  true, false, false);
+#if BITS_PER_LONG == 64
+	TEST_TYPE_SETS(u64, false, false, false, false, false, false,  true, false);
+	TEST_TYPE_SETS(s64, false, false, false, false, false, false, false,  true);
+#endif
+
+	/* Check for macro side-effects. */
+	var = 4;
+	KUNIT_EXPECT_EQ(test, var, 4);
+	KUNIT_EXPECT_TRUE(test, __same_type(var++, int));
+	KUNIT_EXPECT_EQ(test, var, 4);
+	KUNIT_EXPECT_TRUE(test, __same_type(int, var++));
+	KUNIT_EXPECT_EQ(test, var, 4);
+	KUNIT_EXPECT_TRUE(test, __same_type(var++, var++));
+	KUNIT_EXPECT_EQ(test, var, 4);
+
+	kunit_info(test, "%d __same_type() tests finished\n", count);
+
+#undef TEST_TYPE_SETS
+#undef TEST_SAME_TYPE64
+#undef TEST_SAME_TYPE
+}
+
+static void castable_to_type_test(struct kunit *test)
+{
+	int count = 0;
+
+#define TEST_CASTABLE_TO_TYPE(arg1, arg2, pass)	do {	\
+	bool __pass = castable_to_type(arg1, arg2);		\
+	KUNIT_EXPECT_EQ_MSG(test, __pass, pass,			\
+		"expected castable_to_type(" #arg1 ", " #arg2 ") to%s pass\n",\
+		pass ? "" : " not");				\
+	count++;						\
+} while (0)
+
+	TEST_CASTABLE_TO_TYPE(16, u8, true);
+	TEST_CASTABLE_TO_TYPE(16, u16, true);
+	TEST_CASTABLE_TO_TYPE(16, u32, true);
+	TEST_CASTABLE_TO_TYPE(16, s8, true);
+	TEST_CASTABLE_TO_TYPE(16, s16, true);
+	TEST_CASTABLE_TO_TYPE(16, s32, true);
+	TEST_CASTABLE_TO_TYPE(-16, s8, true);
+	TEST_CASTABLE_TO_TYPE(-16, s16, true);
+	TEST_CASTABLE_TO_TYPE(-16, s32, true);
+#if BITS_PER_LONG == 64
+	TEST_CASTABLE_TO_TYPE(16, u64, true);
+	TEST_CASTABLE_TO_TYPE(-16, s64, true);
+#endif
+
+#define TEST_CASTABLE_TO_TYPE_VAR(width)	do {				\
+	u ## width u ## width ## var = 0;					\
+	s ## width s ## width ## var = 0;					\
+										\
+	/* Constant expressions that fit types. */				\
+	TEST_CASTABLE_TO_TYPE(type_max(u ## width), u ## width, true);		\
+	TEST_CASTABLE_TO_TYPE(type_min(u ## width), u ## width, true);		\
+	TEST_CASTABLE_TO_TYPE(type_max(u ## width), u ## width ## var, true);	\
+	TEST_CASTABLE_TO_TYPE(type_min(u ## width), u ## width ## var, true);	\
+	TEST_CASTABLE_TO_TYPE(type_max(s ## width), s ## width, true);		\
+	TEST_CASTABLE_TO_TYPE(type_min(s ## width), s ## width, true);		\
+	TEST_CASTABLE_TO_TYPE(type_max(s ## width), s ## width ## var, true);	\
+	TEST_CASTABLE_TO_TYPE(type_min(u ## width), s ## width ## var, true);	\
+	/* Constant expressions that do not fit types. */			\
+	TEST_CASTABLE_TO_TYPE(type_max(u ## width), s ## width, false);		\
+	TEST_CASTABLE_TO_TYPE(type_max(u ## width), s ## width ## var, false);	\
+	TEST_CASTABLE_TO_TYPE(type_min(s ## width), u ## width, false);		\
+	TEST_CASTABLE_TO_TYPE(type_min(s ## width), u ## width ## var, false);	\
+	/* Non-constant expression with mismatched type. */			\
+	TEST_CASTABLE_TO_TYPE(s ## width ## var, u ## width, false);		\
+	TEST_CASTABLE_TO_TYPE(u ## width ## var, s ## width, false);		\
+} while (0)
+
+#define TEST_CASTABLE_TO_TYPE_RANGE(width)	do {				\
+	unsigned long big = U ## width ## _MAX;					\
+	signed long small = S ## width ## _MIN;					\
+	u ## width u ## width ## var = 0;					\
+	s ## width s ## width ## var = 0;					\
+										\
+	/* Constant expression in range. */					\
+	TEST_CASTABLE_TO_TYPE(U ## width ## _MAX, u ## width, true);		\
+	TEST_CASTABLE_TO_TYPE(U ## width ## _MAX, u ## width ## var, true);	\
+	TEST_CASTABLE_TO_TYPE(S ## width ## _MIN, s ## width, true);		\
+	TEST_CASTABLE_TO_TYPE(S ## width ## _MIN, s ## width ## var, true);	\
+	/* Constant expression out of range. */					\
+	TEST_CASTABLE_TO_TYPE((unsigned long)U ## width ## _MAX + 1, u ## width, false); \
+	TEST_CASTABLE_TO_TYPE((unsigned long)U ## width ## _MAX + 1, u ## width ## var, false); \
+	TEST_CASTABLE_TO_TYPE((signed long)S ## width ## _MIN - 1, s ## width, false); \
+	TEST_CASTABLE_TO_TYPE((signed long)S ## width ## _MIN - 1, s ## width ## var, false); \
+	/* Non-constant expression with mismatched type. */			\
+	TEST_CASTABLE_TO_TYPE(big, u ## width, false);				\
+	TEST_CASTABLE_TO_TYPE(big, u ## width ## var, false);			\
+	TEST_CASTABLE_TO_TYPE(small, s ## width, false);			\
+	TEST_CASTABLE_TO_TYPE(small, s ## width ## var, false);			\
+} while (0)
+
+	TEST_CASTABLE_TO_TYPE_VAR(8);
+	TEST_CASTABLE_TO_TYPE_VAR(16);
+	TEST_CASTABLE_TO_TYPE_VAR(32);
+#if BITS_PER_LONG == 64
+	TEST_CASTABLE_TO_TYPE_VAR(64);
+#endif
+
+	TEST_CASTABLE_TO_TYPE_RANGE(8);
+	TEST_CASTABLE_TO_TYPE_RANGE(16);
+#if BITS_PER_LONG == 64
+	TEST_CASTABLE_TO_TYPE_RANGE(32);
+#endif
+	kunit_info(test, "%d castable_to_type() tests finished\n", count);
+
+#undef TEST_CASTABLE_TO_TYPE_RANGE
+#undef TEST_CASTABLE_TO_TYPE_VAR
+#undef TEST_CASTABLE_TO_TYPE
+}
+
 static struct kunit_case overflow_test_cases[] = {
 	KUNIT_CASE(u8_u8__u8_overflow_test),
 	KUNIT_CASE(s8_s8__s8_overflow_test),
@@ -755,6 +1133,9 @@ static struct kunit_case overflow_test_cases[] = {
 	KUNIT_CASE(shift_nonsense_test),
 	KUNIT_CASE(overflow_allocation_test),
 	KUNIT_CASE(overflow_size_helpers_test),
+	KUNIT_CASE(overflows_type_test),
+	KUNIT_CASE(same_type_test),
+	KUNIT_CASE(castable_to_type_test),
 	{}
 };
 
diff --git a/lib/test_siphash.c b/lib/siphash_kunit.c
index a96788d0141d..a3c697e8be35 100644
--- a/lib/test_siphash.c
+++ b/lib/siphash_kunit.c
@@ -13,6 +13,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <kunit/test.h>
 #include <linux/siphash.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
@@ -109,114 +110,88 @@ static const u32 test_vectors_hsiphash[64] = {
 };
 #endif
 
-static int __init siphash_test_init(void)
+#define chk(hash, vector, fmt...)			\
+	KUNIT_EXPECT_EQ_MSG(test, hash, vector, fmt)
+
+static void siphash_test(struct kunit *test)
 {
 	u8 in[64] __aligned(SIPHASH_ALIGNMENT);
 	u8 in_unaligned[65] __aligned(SIPHASH_ALIGNMENT);
 	u8 i;
-	int ret = 0;
 
 	for (i = 0; i < 64; ++i) {
 		in[i] = i;
 		in_unaligned[i + 1] = i;
-		if (siphash(in, i, &test_key_siphash) !=
-						test_vectors_siphash[i]) {
-			pr_info("siphash self-test aligned %u: FAIL\n", i + 1);
-			ret = -EINVAL;
-		}
-		if (siphash(in_unaligned + 1, i, &test_key_siphash) !=
-						test_vectors_siphash[i]) {
-			pr_info("siphash self-test unaligned %u: FAIL\n", i + 1);
-			ret = -EINVAL;
-		}
-		if (hsiphash(in, i, &test_key_hsiphash) !=
-						test_vectors_hsiphash[i]) {
-			pr_info("hsiphash self-test aligned %u: FAIL\n", i + 1);
-			ret = -EINVAL;
-		}
-		if (hsiphash(in_unaligned + 1, i, &test_key_hsiphash) !=
-						test_vectors_hsiphash[i]) {
-			pr_info("hsiphash self-test unaligned %u: FAIL\n", i + 1);
-			ret = -EINVAL;
-		}
-	}
-	if (siphash_1u64(0x0706050403020100ULL, &test_key_siphash) !=
-						test_vectors_siphash[8]) {
-		pr_info("siphash self-test 1u64: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (siphash_2u64(0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL,
-			 &test_key_siphash) != test_vectors_siphash[16]) {
-		pr_info("siphash self-test 2u64: FAIL\n");
-		ret = -EINVAL;
+		chk(siphash(in, i, &test_key_siphash),
+		    test_vectors_siphash[i],
+		    "siphash self-test aligned %u: FAIL", i + 1);
+		chk(siphash(in_unaligned + 1, i, &test_key_siphash),
+		    test_vectors_siphash[i],
+		    "siphash self-test unaligned %u: FAIL", i + 1);
+		chk(hsiphash(in, i, &test_key_hsiphash),
+		    test_vectors_hsiphash[i],
+		    "hsiphash self-test aligned %u: FAIL", i + 1);
+		chk(hsiphash(in_unaligned + 1, i, &test_key_hsiphash),
+		    test_vectors_hsiphash[i],
+		    "hsiphash self-test unaligned %u: FAIL", i + 1);
 	}
-	if (siphash_3u64(0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL,
-			 0x1716151413121110ULL, &test_key_siphash) !=
-						test_vectors_siphash[24]) {
-		pr_info("siphash self-test 3u64: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (siphash_4u64(0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL,
+	chk(siphash_1u64(0x0706050403020100ULL, &test_key_siphash),
+	    test_vectors_siphash[8],
+	    "siphash self-test 1u64: FAIL");
+	chk(siphash_2u64(0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL,
+			 &test_key_siphash),
+	    test_vectors_siphash[16],
+	    "siphash self-test 2u64: FAIL");
+	chk(siphash_3u64(0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL,
+			 0x1716151413121110ULL, &test_key_siphash),
+	    test_vectors_siphash[24],
+	    "siphash self-test 3u64: FAIL");
+	chk(siphash_4u64(0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL,
 			 0x1716151413121110ULL, 0x1f1e1d1c1b1a1918ULL,
-			 &test_key_siphash) != test_vectors_siphash[32]) {
-		pr_info("siphash self-test 4u64: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (siphash_1u32(0x03020100U, &test_key_siphash) !=
-						test_vectors_siphash[4]) {
-		pr_info("siphash self-test 1u32: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (siphash_2u32(0x03020100U, 0x07060504U, &test_key_siphash) !=
-						test_vectors_siphash[8]) {
-		pr_info("siphash self-test 2u32: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (siphash_3u32(0x03020100U, 0x07060504U,
-			 0x0b0a0908U, &test_key_siphash) !=
-						test_vectors_siphash[12]) {
-		pr_info("siphash self-test 3u32: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (siphash_4u32(0x03020100U, 0x07060504U,
-			 0x0b0a0908U, 0x0f0e0d0cU, &test_key_siphash) !=
-						test_vectors_siphash[16]) {
-		pr_info("siphash self-test 4u32: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (hsiphash_1u32(0x03020100U, &test_key_hsiphash) !=
-						test_vectors_hsiphash[4]) {
-		pr_info("hsiphash self-test 1u32: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (hsiphash_2u32(0x03020100U, 0x07060504U, &test_key_hsiphash) !=
-						test_vectors_hsiphash[8]) {
-		pr_info("hsiphash self-test 2u32: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (hsiphash_3u32(0x03020100U, 0x07060504U,
-			  0x0b0a0908U, &test_key_hsiphash) !=
-						test_vectors_hsiphash[12]) {
-		pr_info("hsiphash self-test 3u32: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (hsiphash_4u32(0x03020100U, 0x07060504U,
-			  0x0b0a0908U, 0x0f0e0d0cU, &test_key_hsiphash) !=
-						test_vectors_hsiphash[16]) {
-		pr_info("hsiphash self-test 4u32: FAIL\n");
-		ret = -EINVAL;
-	}
-	if (!ret)
-		pr_info("self-tests: pass\n");
-	return ret;
+			 &test_key_siphash),
+	    test_vectors_siphash[32],
+	    "siphash self-test 4u64: FAIL");
+	chk(siphash_1u32(0x03020100U, &test_key_siphash),
+	    test_vectors_siphash[4],
+	    "siphash self-test 1u32: FAIL");
+	chk(siphash_2u32(0x03020100U, 0x07060504U, &test_key_siphash),
+	    test_vectors_siphash[8],
+	    "siphash self-test 2u32: FAIL");
+	chk(siphash_3u32(0x03020100U, 0x07060504U,
+			 0x0b0a0908U, &test_key_siphash),
+	    test_vectors_siphash[12],
+	    "siphash self-test 3u32: FAIL");
+	chk(siphash_4u32(0x03020100U, 0x07060504U,
+			 0x0b0a0908U, 0x0f0e0d0cU, &test_key_siphash),
+	    test_vectors_siphash[16],
+	    "siphash self-test 4u32: FAIL");
+	chk(hsiphash_1u32(0x03020100U, &test_key_hsiphash),
+	    test_vectors_hsiphash[4],
+	    "hsiphash self-test 1u32: FAIL");
+	chk(hsiphash_2u32(0x03020100U, 0x07060504U, &test_key_hsiphash),
+	    test_vectors_hsiphash[8],
+	    "hsiphash self-test 2u32: FAIL");
+	chk(hsiphash_3u32(0x03020100U, 0x07060504U,
+			  0x0b0a0908U, &test_key_hsiphash),
+	    test_vectors_hsiphash[12],
+	    "hsiphash self-test 3u32: FAIL");
+	chk(hsiphash_4u32(0x03020100U, 0x07060504U,
+			  0x0b0a0908U, 0x0f0e0d0cU, &test_key_hsiphash),
+	    test_vectors_hsiphash[16],
+	    "hsiphash self-test 4u32: FAIL");
 }
 
-static void __exit siphash_test_exit(void)
-{
-}
+static struct kunit_case siphash_test_cases[] = {
+	KUNIT_CASE(siphash_test),
+	{}
+};
+
+static struct kunit_suite siphash_test_suite = {
+	.name = "siphash",
+	.test_cases = siphash_test_cases,
+};
 
-module_init(siphash_test_init);
-module_exit(siphash_test_exit);
+kunit_test_suite(siphash_test_suite);
 
 MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
 MODULE_LICENSE("Dual BSD/GPL");
diff --git a/lib/string.c b/lib/string.c
index 3371d26a0e39..4fb566ea610f 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -76,11 +76,6 @@ EXPORT_SYMBOL(strcasecmp);
 #endif
 
 #ifndef __HAVE_ARCH_STRCPY
-/**
- * strcpy - Copy a %NUL terminated string
- * @dest: Where to copy the string to
- * @src: Where to copy the string from
- */
 char *strcpy(char *dest, const char *src)
 {
 	char *tmp = dest;
@@ -93,19 +88,6 @@ EXPORT_SYMBOL(strcpy);
 #endif
 
 #ifndef __HAVE_ARCH_STRNCPY
-/**
- * strncpy - Copy a length-limited, C-string
- * @dest: Where to copy the string to
- * @src: Where to copy the string from
- * @count: The maximum number of bytes to copy
- *
- * The result is not %NUL-terminated if the source exceeds
- * @count bytes.
- *
- * In the case where the length of @src is less than  that  of
- * count, the remainder of @dest will be padded with %NUL.
- *
- */
 char *strncpy(char *dest, const char *src, size_t count)
 {
 	char *tmp = dest;
@@ -122,17 +104,6 @@ EXPORT_SYMBOL(strncpy);
 #endif
 
 #ifndef __HAVE_ARCH_STRLCPY
-/**
- * strlcpy - Copy a C-string into a sized buffer
- * @dest: Where to copy the string to
- * @src: Where to copy the string from
- * @size: size of destination buffer
- *
- * Compatible with ``*BSD``: the result is always a valid
- * NUL-terminated string that fits in the buffer (unless,
- * of course, the buffer size is zero). It does not pad
- * out the result like strncpy() does.
- */
 size_t strlcpy(char *dest, const char *src, size_t size)
 {
 	size_t ret = strlen(src);
@@ -148,30 +119,6 @@ EXPORT_SYMBOL(strlcpy);
 #endif
 
 #ifndef __HAVE_ARCH_STRSCPY
-/**
- * strscpy - Copy a C-string into a sized buffer
- * @dest: Where to copy the string to
- * @src: Where to copy the string from
- * @count: Size of destination buffer
- *
- * Copy the string, or as much of it as fits, into the dest buffer.  The
- * behavior is undefined if the string buffers overlap.  The destination
- * buffer is always NUL terminated, unless it's zero-sized.
- *
- * Preferred to strlcpy() since the API doesn't require reading memory
- * from the src string beyond the specified "count" bytes, and since
- * the return value is easier to error-check than strlcpy()'s.
- * In addition, the implementation is robust to the string changing out
- * from underneath it, unlike the current strlcpy() implementation.
- *
- * Preferred to strncpy() since it always returns a valid string, and
- * doesn't unnecessarily force the tail of the destination buffer to be
- * zeroed.  If zeroing is desired please use strscpy_pad().
- *
- * Returns:
- * * The number of characters copied (not including the trailing %NUL)
- * * -E2BIG if count is 0 or @src was truncated.
- */
 ssize_t strscpy(char *dest, const char *src, size_t count)
 {
 	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
@@ -266,11 +213,6 @@ char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
 EXPORT_SYMBOL(stpcpy);
 
 #ifndef __HAVE_ARCH_STRCAT
-/**
- * strcat - Append one %NUL-terminated string to another
- * @dest: The string to be appended to
- * @src: The string to append to it
- */
 char *strcat(char *dest, const char *src)
 {
 	char *tmp = dest;
@@ -285,15 +227,6 @@ EXPORT_SYMBOL(strcat);
 #endif
 
 #ifndef __HAVE_ARCH_STRNCAT
-/**
- * strncat - Append a length-limited, C-string to another
- * @dest: The string to be appended to
- * @src: The string to append to it
- * @count: The maximum numbers of bytes to copy
- *
- * Note that in contrast to strncpy(), strncat() ensures the result is
- * terminated.
- */
 char *strncat(char *dest, const char *src, size_t count)
 {
 	char *tmp = dest;
@@ -314,12 +247,6 @@ EXPORT_SYMBOL(strncat);
 #endif
 
 #ifndef __HAVE_ARCH_STRLCAT
-/**
- * strlcat - Append a length-limited, C-string to another
- * @dest: The string to be appended to
- * @src: The string to append to it
- * @count: The size of the destination buffer.
- */
 size_t strlcat(char *dest, const char *src, size_t count)
 {
 	size_t dsize = strlen(dest);
@@ -484,10 +411,6 @@ EXPORT_SYMBOL(strnchr);
 #endif
 
 #ifndef __HAVE_ARCH_STRLEN
-/**
- * strlen - Find the length of a string
- * @s: The string to be sized
- */
 size_t strlen(const char *s)
 {
 	const char *sc;
@@ -500,11 +423,6 @@ EXPORT_SYMBOL(strlen);
 #endif
 
 #ifndef __HAVE_ARCH_STRNLEN
-/**
- * strnlen - Find the length of a length-limited string
- * @s: The string to be sized
- * @count: The maximum number of bytes to search
- */
 size_t strnlen(const char *s, size_t count)
 {
 	const char *sc;
diff --git a/lib/strscpy_kunit.c b/lib/strscpy_kunit.c
new file mode 100644
index 000000000000..a6b6344354ed
--- /dev/null
+++ b/lib/strscpy_kunit.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Kernel module for testing 'strscpy' family of functions.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <kunit/test.h>
+#include <linux/string.h>
+
+/*
+ * tc() - Run a specific test case.
+ * @src: Source string, argument to strscpy_pad()
+ * @count: Size of destination buffer, argument to strscpy_pad()
+ * @expected: Expected return value from call to strscpy_pad()
+ * @terminator: 1 if there should be a terminating null byte 0 otherwise.
+ * @chars: Number of characters from the src string expected to be
+ *         written to the dst buffer.
+ * @pad: Number of pad characters expected (in the tail of dst buffer).
+ *       (@pad does not include the null terminator byte.)
+ *
+ * Calls strscpy_pad() and verifies the return value and state of the
+ * destination buffer after the call returns.
+ */
+static void tc(struct kunit *test, char *src, int count, int expected,
+	       int chars, int terminator, int pad)
+{
+	int nr_bytes_poison;
+	int max_expected;
+	int max_count;
+	int written;
+	char buf[6];
+	int index, i;
+	const char POISON = 'z';
+
+	KUNIT_ASSERT_TRUE_MSG(test, src != NULL,
+			      "null source string not supported");
+
+	memset(buf, POISON, sizeof(buf));
+	/* Future proofing test suite, validate args */
+	max_count = sizeof(buf) - 2; /* Space for null and to verify overflow */
+	max_expected = count - 1;    /* Space for the null */
+
+	KUNIT_ASSERT_LE_MSG(test, count, max_count,
+		"count (%d) is too big (%d) ... aborting", count, max_count);
+	KUNIT_EXPECT_LE_MSG(test, expected, max_expected,
+		"expected (%d) is bigger than can possibly be returned (%d)",
+		expected, max_expected);
+
+	written = strscpy_pad(buf, src, count);
+	KUNIT_ASSERT_EQ(test, written, expected);
+
+	if (count && written == -E2BIG) {
+		KUNIT_ASSERT_EQ_MSG(test, 0, strncmp(buf, src, count - 1),
+			"buffer state invalid for -E2BIG");
+		KUNIT_ASSERT_EQ_MSG(test, buf[count - 1], '\0',
+			"too big string is not null terminated correctly");
+	}
+
+	for (i = 0; i < chars; i++)
+		KUNIT_ASSERT_EQ_MSG(test, buf[i], src[i],
+			"buf[i]==%c != src[i]==%c", buf[i], src[i]);
+
+	if (terminator)
+		KUNIT_ASSERT_EQ_MSG(test, buf[count - 1], '\0',
+			"string is not null terminated correctly");
+
+	for (i = 0; i < pad; i++) {
+		index = chars + terminator + i;
+		KUNIT_ASSERT_EQ_MSG(test, buf[index], '\0',
+			"padding missing at index: %d", i);
+	}
+
+	nr_bytes_poison = sizeof(buf) - chars - terminator - pad;
+	for (i = 0; i < nr_bytes_poison; i++) {
+		index = sizeof(buf) - 1 - i; /* Check from the end back */
+		KUNIT_ASSERT_EQ_MSG(test, buf[index], POISON,
+			"poison value missing at index: %d", i);
+	}
+}
+
+static void strscpy_test(struct kunit *test)
+{
+	char dest[8];
+
+	/*
+	 * tc() uses a destination buffer of size 6 and needs at
+	 * least 2 characters spare (one for null and one to check for
+	 * overflow).  This means we should only call tc() with
+	 * strings up to a maximum of 4 characters long and 'count'
+	 * should not exceed 4.  To test with longer strings increase
+	 * the buffer size in tc().
+	 */
+
+	/* tc(test, src, count, expected, chars, terminator, pad) */
+	tc(test, "a", 0, -E2BIG, 0, 0, 0);
+	tc(test, "",  0, -E2BIG, 0, 0, 0);
+
+	tc(test, "a", 1, -E2BIG, 0, 1, 0);
+	tc(test, "",  1, 0,	 0, 1, 0);
+
+	tc(test, "ab", 2, -E2BIG, 1, 1, 0);
+	tc(test, "a",  2, 1,	  1, 1, 0);
+	tc(test, "",   2, 0,	  0, 1, 1);
+
+	tc(test, "abc", 3, -E2BIG, 2, 1, 0);
+	tc(test, "ab",  3, 2,	   2, 1, 0);
+	tc(test, "a",   3, 1,	   1, 1, 1);
+	tc(test, "",    3, 0,	   0, 1, 2);
+
+	tc(test, "abcd", 4, -E2BIG, 3, 1, 0);
+	tc(test, "abc",  4, 3,	    3, 1, 0);
+	tc(test, "ab",   4, 2,	    2, 1, 1);
+	tc(test, "a",    4, 1,	    1, 1, 2);
+	tc(test, "",     4, 0,	    0, 1, 3);
+
+	/* Compile-time-known source strings. */
+	KUNIT_EXPECT_EQ(test, strscpy(dest, "", ARRAY_SIZE(dest)), 0);
+	KUNIT_EXPECT_EQ(test, strscpy(dest, "", 3), 0);
+	KUNIT_EXPECT_EQ(test, strscpy(dest, "", 1), 0);
+	KUNIT_EXPECT_EQ(test, strscpy(dest, "", 0), -E2BIG);
+	KUNIT_EXPECT_EQ(test, strscpy(dest, "Fixed", ARRAY_SIZE(dest)), 5);
+	KUNIT_EXPECT_EQ(test, strscpy(dest, "Fixed", 3), -E2BIG);
+	KUNIT_EXPECT_EQ(test, strscpy(dest, "Fixed", 1), -E2BIG);
+	KUNIT_EXPECT_EQ(test, strscpy(dest, "Fixed", 0), -E2BIG);
+	KUNIT_EXPECT_EQ(test, strscpy(dest, "This is too long", ARRAY_SIZE(dest)), -E2BIG);
+}
+
+static struct kunit_case strscpy_test_cases[] = {
+	KUNIT_CASE(strscpy_test),
+	{}
+};
+
+static struct kunit_suite strscpy_test_suite = {
+	.name = "strscpy",
+	.test_cases = strscpy_test_cases,
+};
+
+kunit_test_suite(strscpy_test_suite);
+
+MODULE_AUTHOR("Tobin C. Harding <tobin@kernel.org>");
+MODULE_LICENSE("GPL");
diff --git a/lib/test_strscpy.c b/lib/test_strscpy.c
deleted file mode 100644
index a827f94601f5..000000000000
--- a/lib/test_strscpy.c
+++ /dev/null
@@ -1,150 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0+
-
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#include <linux/string.h>
-
-#include "../tools/testing/selftests/kselftest_module.h"
-
-/*
- * Kernel module for testing 'strscpy' family of functions.
- */
-
-KSTM_MODULE_GLOBALS();
-
-/*
- * tc() - Run a specific test case.
- * @src: Source string, argument to strscpy_pad()
- * @count: Size of destination buffer, argument to strscpy_pad()
- * @expected: Expected return value from call to strscpy_pad()
- * @terminator: 1 if there should be a terminating null byte 0 otherwise.
- * @chars: Number of characters from the src string expected to be
- *         written to the dst buffer.
- * @pad: Number of pad characters expected (in the tail of dst buffer).
- *       (@pad does not include the null terminator byte.)
- *
- * Calls strscpy_pad() and verifies the return value and state of the
- * destination buffer after the call returns.
- */
-static int __init tc(char *src, int count, int expected,
-		     int chars, int terminator, int pad)
-{
-	int nr_bytes_poison;
-	int max_expected;
-	int max_count;
-	int written;
-	char buf[6];
-	int index, i;
-	const char POISON = 'z';
-
-	total_tests++;
-
-	if (!src) {
-		pr_err("null source string not supported\n");
-		return -1;
-	}
-
-	memset(buf, POISON, sizeof(buf));
-	/* Future proofing test suite, validate args */
-	max_count = sizeof(buf) - 2; /* Space for null and to verify overflow */
-	max_expected = count - 1;    /* Space for the null */
-	if (count > max_count) {
-		pr_err("count (%d) is too big (%d) ... aborting", count, max_count);
-		return -1;
-	}
-	if (expected > max_expected) {
-		pr_warn("expected (%d) is bigger than can possibly be returned (%d)",
-			expected, max_expected);
-	}
-
-	written = strscpy_pad(buf, src, count);
-	if ((written) != (expected)) {
-		pr_err("%d != %d (written, expected)\n", written, expected);
-		goto fail;
-	}
-
-	if (count && written == -E2BIG) {
-		if (strncmp(buf, src, count - 1) != 0) {
-			pr_err("buffer state invalid for -E2BIG\n");
-			goto fail;
-		}
-		if (buf[count - 1] != '\0') {
-			pr_err("too big string is not null terminated correctly\n");
-			goto fail;
-		}
-	}
-
-	for (i = 0; i < chars; i++) {
-		if (buf[i] != src[i]) {
-			pr_err("buf[i]==%c != src[i]==%c\n", buf[i], src[i]);
-			goto fail;
-		}
-	}
-
-	if (terminator) {
-		if (buf[count - 1] != '\0') {
-			pr_err("string is not null terminated correctly\n");
-			goto fail;
-		}
-	}
-
-	for (i = 0; i < pad; i++) {
-		index = chars + terminator + i;
-		if (buf[index] != '\0') {
-			pr_err("padding missing at index: %d\n", i);
-			goto fail;
-		}
-	}
-
-	nr_bytes_poison = sizeof(buf) - chars - terminator - pad;
-	for (i = 0; i < nr_bytes_poison; i++) {
-		index = sizeof(buf) - 1 - i; /* Check from the end back */
-		if (buf[index] != POISON) {
-			pr_err("poison value missing at index: %d\n", i);
-			goto fail;
-		}
-	}
-
-	return 0;
-fail:
-	failed_tests++;
-	return -1;
-}
-
-static void __init selftest(void)
-{
-	/*
-	 * tc() uses a destination buffer of size 6 and needs at
-	 * least 2 characters spare (one for null and one to check for
-	 * overflow).  This means we should only call tc() with
-	 * strings up to a maximum of 4 characters long and 'count'
-	 * should not exceed 4.  To test with longer strings increase
-	 * the buffer size in tc().
-	 */
-
-	/* tc(src, count, expected, chars, terminator, pad) */
-	KSTM_CHECK_ZERO(tc("a", 0, -E2BIG, 0, 0, 0));
-	KSTM_CHECK_ZERO(tc("", 0, -E2BIG, 0, 0, 0));
-
-	KSTM_CHECK_ZERO(tc("a", 1, -E2BIG, 0, 1, 0));
-	KSTM_CHECK_ZERO(tc("", 1, 0, 0, 1, 0));
-
-	KSTM_CHECK_ZERO(tc("ab", 2, -E2BIG, 1, 1, 0));
-	KSTM_CHECK_ZERO(tc("a", 2, 1, 1, 1, 0));
-	KSTM_CHECK_ZERO(tc("", 2, 0, 0, 1, 1));
-
-	KSTM_CHECK_ZERO(tc("abc", 3, -E2BIG, 2, 1, 0));
-	KSTM_CHECK_ZERO(tc("ab", 3, 2, 2, 1, 0));
-	KSTM_CHECK_ZERO(tc("a", 3, 1, 1, 1, 1));
-	KSTM_CHECK_ZERO(tc("", 3, 0, 0, 1, 2));
-
-	KSTM_CHECK_ZERO(tc("abcd", 4, -E2BIG, 3, 1, 0));
-	KSTM_CHECK_ZERO(tc("abc", 4, 3, 3, 1, 0));
-	KSTM_CHECK_ZERO(tc("ab", 4, 2, 2, 1, 1));
-	KSTM_CHECK_ZERO(tc("a", 4, 1, 1, 1, 2));
-	KSTM_CHECK_ZERO(tc("", 4, 0, 0, 1, 3));
-}
-
-KSTM_MODULE_LOADERS(test_strscpy);
-MODULE_AUTHOR("Tobin C. Harding <tobin@kernel.org>");
-MODULE_LICENSE("GPL");
diff --git a/lib/ubsan.c b/lib/ubsan.c
index 36bd75e33426..60c7099857a0 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -154,8 +154,7 @@ static void ubsan_epilogue(void)
 
 	current->in_ubsan--;
 
-	if (panic_on_warn)
-		panic("panic_on_warn set ...\n");
+	check_panic_on_warn("UBSAN");
 }
 
 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)