// SPDX-License-Identifier: GPL-2.0
/*
 * Runtime test cases for CONFIG_FORTIFY_SOURCE. For additional memcpy()
 * testing see FORTIFY_MEM_* tests in LKDTM (drivers/misc/lkdtm/fortify.c).
 *
 * For corner cases with UBSAN, try testing with:
 *
 * ./tools/testing/kunit/kunit.py run --arch=x86_64 \
 *      --kconfig_add CONFIG_FORTIFY_SOURCE=y \
 *      --kconfig_add CONFIG_UBSAN=y \
 *      --kconfig_add CONFIG_UBSAN_TRAP=y \
 *      --kconfig_add CONFIG_UBSAN_BOUNDS=y \
 *      --kconfig_add CONFIG_UBSAN_LOCAL_BOUNDS=y \
 *      --make_options LLVM=1 fortify
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

/* We don't need to fill dmesg with the fortify WARNs during testing. */
#ifdef DEBUG
# define FORTIFY_REPORT_KUNIT(x...) __fortify_report(x)
# define FORTIFY_WARN_KUNIT(x...)   WARN_ONCE(x)
#else
# define FORTIFY_REPORT_KUNIT(x...) do { } while (0)
# define FORTIFY_WARN_KUNIT(x...)   do { } while (0)
#endif

/* Redefine fortify_panic() to track failures. */
void fortify_add_kunit_error(int write);
#define fortify_panic(func, write, avail, size, retfail) do {           \
        FORTIFY_REPORT_KUNIT(FORTIFY_REASON(func, write), avail, size); \
        fortify_add_kunit_error(write);                                 \
        return (retfail);                                               \
} while (0)

/* Redefine fortify_warn_once() to track memcpy() failures. */
#define fortify_warn_once(chk_func, x...) do {                          \
        bool __result = chk_func;                                       \
        FORTIFY_WARN_KUNIT(__result, x);                                \
        if (__result)                                                   \
                fortify_add_kunit_error(1);                             \
} while (0)

#include <kunit/device.h>
#include <kunit/test.h>
#include <kunit/test-bug.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/vmalloc.h>

/* Handle being built without CONFIG_FORTIFY_SOURCE */
#ifndef __compiletime_strlen
# define __compiletime_strlen __builtin_strlen
#endif

static struct kunit_resource read_resource;
static struct kunit_resource write_resource;
static int fortify_read_overflows;
static int fortify_write_overflows;

static const char array_of_10[] = "this is 10";
static const char *ptr_of_11 = "this is 11!";
static const char * const unchanging_12 = "this is 12!!";
static char array_unknown[] = "compiler thinks I might change";

void fortify_add_kunit_error(int write)
{
        struct kunit_resource *resource;
        struct kunit *current_test;

        current_test = kunit_get_current_test();
        if (!current_test)
                return;

        resource = kunit_find_named_resource(current_test,
                        write ? "fortify_write_overflows"
                              : "fortify_read_overflows");
        if (!resource)
                return;

        (*(int *)resource->data)++;
        kunit_put_resource(resource);
}

static void fortify_test_known_sizes(struct kunit *test)
{
        char stack[80] = "Test!";

        KUNIT_EXPECT_FALSE(test, __is_constexpr(__builtin_strlen(stack)));
        KUNIT_EXPECT_EQ(test, __compiletime_strlen(stack), 5);

        KUNIT_EXPECT_TRUE(test, __is_constexpr(__builtin_strlen("88888888")));
        KUNIT_EXPECT_EQ(test, __compiletime_strlen("88888888"), 8);

        KUNIT_EXPECT_TRUE(test, __is_constexpr(__builtin_strlen(array_of_10)));
        KUNIT_EXPECT_EQ(test, __compiletime_strlen(array_of_10), 10);

        KUNIT_EXPECT_FALSE(test, __is_constexpr(__builtin_strlen(ptr_of_11)));
        KUNIT_EXPECT_EQ(test, __compiletime_strlen(ptr_of_11), 11);

        KUNIT_EXPECT_TRUE(test, __is_constexpr(__builtin_strlen(unchanging_12)));
        KUNIT_EXPECT_EQ(test, __compiletime_strlen(unchanging_12), 12);

        KUNIT_EXPECT_FALSE(test, __is_constexpr(__builtin_strlen(array_unknown)));
        KUNIT_EXPECT_EQ(test, __compiletime_strlen(array_unknown), SIZE_MAX);

        /* Externally defined and dynamically sized string pointer: */
        KUNIT_EXPECT_FALSE(test, __is_constexpr(__builtin_strlen(test->name)));
        KUNIT_EXPECT_EQ(test, __compiletime_strlen(test->name), SIZE_MAX);
}

/* This is volatile so the optimizer can't perform DCE below. */
static volatile int pick;

/* Not inline to keep optimizer from figuring out which string we want. */
static noinline size_t want_minus_one(int pick)
{
        const char *str;

        switch (pick) {
        case 1:
                str = "4444";
                break;
        case 2:
                str = "333";
                break;
        default:
                str = "1";
                break;
        }
        return __compiletime_strlen(str);
}

static void fortify_test_control_flow_split(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 fortify_test_alloc_size_##allocator##_const(struct kunit *test) \
{                                                                       \
        CONST_TEST_BODY(TEST_##allocator);                              \
}                                                                       \
static void fortify_test_alloc_size_##allocator##_dynamic(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));                                              \
                                                                        \
        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),               \
                kvfree(p));                                             \
        checker((expected_pages) * PAGE_SIZE,                           \
                kvmalloc_node((alloc_pages) * PAGE_SIZE, gfp, NUMA_NO_NODE), \
                kvfree(p));                                             \
        checker((expected_pages) * PAGE_SIZE,                           \
                kvzalloc((alloc_pages) * PAGE_SIZE, gfp),               \
                kvfree(p));                                             \
        checker((expected_pages) * PAGE_SIZE,                           \
                kvzalloc_node((alloc_pages) * PAGE_SIZE, gfp, NUMA_NO_NODE), \
                kvfree(p));                                             \
        checker((expected_pages) * PAGE_SIZE,                           \
                kvcalloc(1, (alloc_pages) * PAGE_SIZE, gfp),            \
                kvfree(p));                                             \
        checker((expected_pages) * PAGE_SIZE,                           \
                kvcalloc((alloc_pages) * PAGE_SIZE, 1, gfp),            \
                kvfree(p));                                             \
        checker((expected_pages) * PAGE_SIZE,                           \
                kvmalloc_array(1, (alloc_pages) * PAGE_SIZE, gfp),      \
                kvfree(p));                                             \
        checker((expected_pages) * PAGE_SIZE,                           \
                kvmalloc_array((alloc_pages) * PAGE_SIZE, 1, gfp),      \
                kvfree(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, ((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 = kunit_device_register(test, 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));                                    \
                                                                        \
        kunit_device_unregister(test, dev);                             \
} while (0)
DEFINE_ALLOC_SIZE_TEST_PAIR(devm_kmalloc)

static const char * const test_strs[] = {
        "",
        "Hello there",
        "A longer string, just for variety",
};

#define TEST_realloc(checker)   do {                                    \
        gfp_t gfp = GFP_KERNEL;                                         \
        size_t len;                                                     \
        int i;                                                          \
                                                                        \
        for (i = 0; i < ARRAY_SIZE(test_strs); i++) {                   \
                len = strlen(test_strs[i]);                             \
                KUNIT_EXPECT_EQ(test, __builtin_constant_p(len), 0);    \
                checker(len, kmemdup_array(test_strs[i], 1, len, gfp),  \
                        kfree(p));                                      \
                checker(len, kmemdup(test_strs[i], len, gfp),           \
                        kfree(p));                                      \
        }                                                               \
} while (0)
static void fortify_test_realloc_size(struct kunit *test)
{
        TEST_realloc(check_dynamic);
}

/*
 * We can't have an array at the end of a structure or else
 * builds without -fstrict-flex-arrays=3 will report them as
 * being an unknown length. Additionally, add bytes before
 * and after the string to catch over/underflows if tests
 * fail.
 */
struct fortify_padding {
        unsigned long bytes_before;
        char buf[32];
        unsigned long bytes_after;
};

static void fortify_test_strlen(struct kunit *test)
{
        struct fortify_padding pad = { };
        int i, end = sizeof(pad.buf) - 1;

        /* Fill 31 bytes with valid characters. */
        for (i = 0; i < sizeof(pad.buf) - 1; i++)
                pad.buf[i] = i + '0';
        /* Trailing bytes are still %NUL. */
        KUNIT_EXPECT_EQ(test, pad.buf[end], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* String is terminated, so strlen() is valid. */
        KUNIT_EXPECT_EQ(test, strlen(pad.buf), end);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);

        /* Make string unterminated, and recount. */
        pad.buf[end] = 'A';
        end = sizeof(pad.buf);
        KUNIT_EXPECT_EQ(test, strlen(pad.buf), end);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
}

static void fortify_test_strnlen(struct kunit *test)
{
        struct fortify_padding pad = { };
        int i, end = sizeof(pad.buf) - 1;

        /* Fill 31 bytes with valid characters. */
        for (i = 0; i < sizeof(pad.buf) - 1; i++)
                pad.buf[i] = i + '0';
        /* Trailing bytes are still %NUL. */
        KUNIT_EXPECT_EQ(test, pad.buf[end], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* String is terminated, so strnlen() is valid. */
        KUNIT_EXPECT_EQ(test, strnlen(pad.buf, sizeof(pad.buf)), end);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        /* A truncated strnlen() will be safe, too. */
        KUNIT_EXPECT_EQ(test, strnlen(pad.buf, sizeof(pad.buf) / 2),
                                        sizeof(pad.buf) / 2);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);

        /* Make string unterminated, and recount. */
        pad.buf[end] = 'A';
        end = sizeof(pad.buf);
        /* Reading beyond with strncpy() will fail. */
        KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end + 1), end);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
        KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end + 2), end);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);

        /* Early-truncated is safe still, though. */
        KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end), end);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);

        end = sizeof(pad.buf) / 2;
        KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end), end);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void fortify_test_strcpy(struct kunit *test)
{
        struct fortify_padding pad = { };
        char src[sizeof(pad.buf) + 1] = { };
        int i;

        /* Fill 31 bytes with valid characters. */
        for (i = 0; i < sizeof(src) - 2; i++)
                src[i] = i + '0';

        /* Destination is %NUL-filled to start with. */
        KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Legitimate strcpy() 1 less than of max size. */
        KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src)
                                == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Only last byte should be %NUL */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

        src[sizeof(src) - 2] = 'A';
        /* But now we trip the overflow checking. */
        KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src)
                                == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
        /* Trailing %NUL -- thanks to FORTIFY. */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        /* And we will not have gone beyond. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        src[sizeof(src) - 1] = 'A';
        /* And for sure now, two bytes past. */
        KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src)
                                == pad.buf);
        /*
         * Which trips both the strlen() on the unterminated src,
         * and the resulting copy attempt.
         */
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
        /* Trailing %NUL -- thanks to FORTIFY. */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        /* And we will not have gone beyond. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void fortify_test_strncpy(struct kunit *test)
{
        struct fortify_padding pad = { };
        char src[] = "Copy me fully into a small buffer and I will overflow!";
        size_t sizeof_buf = sizeof(pad.buf);

        OPTIMIZER_HIDE_VAR(sizeof_buf);

        /* Destination is %NUL-filled to start with. */
        KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Legitimate strncpy() 1 less than of max size. */
        KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src, sizeof_buf - 1)
                                == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Only last byte should be %NUL */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 3], '\0');

        /* Legitimate (though unterminated) max-size strncpy. */
        KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src, sizeof_buf)
                                == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* No trailing %NUL -- thanks strncpy API. */
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        /* But we will not have gone beyond. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Now verify that FORTIFY is working... */
        KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src, sizeof_buf + 1)
                                == pad.buf);
        /* Should catch the overflow. */
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        /* And we will not have gone beyond. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* And further... */
        KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src, sizeof_buf + 2)
                                == pad.buf);
        /* Should catch the overflow. */
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        /* And we will not have gone beyond. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void fortify_test_strscpy(struct kunit *test)
{
        struct fortify_padding pad = { };
        char src[] = "Copy me fully into a small buffer and I will overflow!";
        size_t sizeof_buf = sizeof(pad.buf);
        size_t sizeof_src = sizeof(src);

        OPTIMIZER_HIDE_VAR(sizeof_buf);
        OPTIMIZER_HIDE_VAR(sizeof_src);

        /* Destination is %NUL-filled to start with. */
        KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Legitimate strscpy() 1 less than of max size. */
        KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, sizeof_buf - 1),
                        -E2BIG);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Keeping space for %NUL, last two bytes should be %NUL */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 3], '\0');

        /* Legitimate max-size strscpy. */
        KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, sizeof_buf),
                        -E2BIG);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* A trailing %NUL will exist. */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');

        /* Now verify that FORTIFY is working... */
        KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, sizeof_buf + 1),
                        -E2BIG);
        /* Should catch the overflow. */
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        /* And we will not have gone beyond. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* And much further... */
        KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, sizeof_src * 2),
                        -E2BIG);
        /* Should catch the overflow. */
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof_buf - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof_buf - 2], '\0');
        /* And we will not have gone beyond. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void fortify_test_strcat(struct kunit *test)
{
        struct fortify_padding pad = { };
        char src[sizeof(pad.buf) / 2] = { };
        char one[] = "A";
        char two[] = "BC";
        int i;

        /* Fill 15 bytes with valid characters. */
        for (i = 0; i < sizeof(src) - 1; i++)
                src[i] = i + 'A';

        /* Destination is %NUL-filled to start with. */
        KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Legitimate strcat() using less than half max size. */
        KUNIT_ASSERT_TRUE(test, strcat(pad.buf, src) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Legitimate strcat() now 2 bytes shy of end. */
        KUNIT_ASSERT_TRUE(test, strcat(pad.buf, src) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Last two bytes should be %NUL */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

        /* Add one more character to the end. */
        KUNIT_ASSERT_TRUE(test, strcat(pad.buf, one) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Last byte should be %NUL */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

        /* And this one char will overflow. */
        KUNIT_ASSERT_TRUE(test, strcat(pad.buf, one) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
        /* Last byte should be %NUL thanks to FORTIFY. */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* And adding two will overflow more. */
        KUNIT_ASSERT_TRUE(test, strcat(pad.buf, two) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
        /* Last byte should be %NUL thanks to FORTIFY. */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void fortify_test_strncat(struct kunit *test)
{
        struct fortify_padding pad = { };
        char src[sizeof(pad.buf)] = { };
        int i, partial;

        /* Fill 31 bytes with valid characters. */
        partial = sizeof(src) / 2 - 1;
        for (i = 0; i < partial; i++)
                src[i] = i + 'A';

        /* Destination is %NUL-filled to start with. */
        KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Legitimate strncat() using less than half max size. */
        KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, partial) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Legitimate strncat() now 2 bytes shy of end. */
        KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, partial) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Last two bytes should be %NUL */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

        /* Add one more character to the end. */
        KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Last byte should be %NUL */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

        /* And this one char will overflow. */
        KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
        /* Last byte should be %NUL thanks to FORTIFY. */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* And adding two will overflow more. */
        KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 2) == pad.buf);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
        /* Last byte should be %NUL thanks to FORTIFY. */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Force an unterminated destination, and overflow. */
        pad.buf[sizeof(pad.buf) - 1] = 'A';
        KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf);
        /* This will have tripped both strlen() and strcat(). */
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 3);
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        /* But we should not go beyond the end. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void fortify_test_strlcat(struct kunit *test)
{
        struct fortify_padding pad = { };
        char src[sizeof(pad.buf)] = { };
        int i, partial;
        int len = sizeof(pad.buf);

        OPTIMIZER_HIDE_VAR(len);

        /* Fill 15 bytes with valid characters. */
        partial = sizeof(src) / 2 - 1;
        for (i = 0; i < partial; i++)
                src[i] = i + 'A';

        /* Destination is %NUL-filled to start with. */
        KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Legitimate strlcat() using less than half max size. */
        KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len), partial);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Legitimate strlcat() now 2 bytes shy of end. */
        KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len), partial * 2);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Last two bytes should be %NUL */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

        /* Add one more character to the end. */
        KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "Q", len), partial * 2 + 1);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
        /* Last byte should be %NUL */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

        /* And this one char will overflow. */
        KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "V", len * 2), len);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
        /* Last byte should be %NUL thanks to FORTIFY. */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* And adding two will overflow more. */
        KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "QQ", len * 2), len + 1);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
        /* Last byte should be %NUL thanks to FORTIFY. */
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Force an unterminated destination, and overflow. */
        pad.buf[sizeof(pad.buf) - 1] = 'A';
        KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "TT", len * 2), len + 2);
        /* This will have tripped both strlen() and strlcat(). */
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
        KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
        /* But we should not go beyond the end. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

        /* Force an unterminated source, and overflow. */
        memset(src, 'B', sizeof(src));
        pad.buf[sizeof(pad.buf) - 1] = '\0';
        KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len * 3), len - 1 + sizeof(src));
        /* This will have tripped both strlen() and strlcat(). */
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 3);
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 3);
        KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
        /* But we should not go beyond the end. */
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

/* Check for 0-sized arrays... */
struct fortify_zero_sized {
        unsigned long bytes_before;
        char buf[0];
        unsigned long bytes_after;
};

#define __fortify_test(memfunc)                                 \
static void fortify_test_##memfunc(struct kunit *test)          \
{                                                               \
        struct fortify_zero_sized empty = { };                  \
        struct fortify_padding pad = { };                       \
        char srcA[sizeof(pad.buf) + 2];                         \
        char srcB[sizeof(pad.buf) + 2];                         \
        size_t len = sizeof(pad.buf);                           \
        size_t zero = 0;                                        \
                                                                \
        OPTIMIZER_HIDE_VAR(len);                                \
        OPTIMIZER_HIDE_VAR(zero);                               \
                                                                \
        memset(srcA, 'A', sizeof(srcA));                        \
        KUNIT_ASSERT_EQ(test, srcA[0], 'A');                    \
        memset(srcB, 'B', sizeof(srcB));                        \
        KUNIT_ASSERT_EQ(test, srcB[0], 'B');                    \
                                                                \
        memfunc(pad.buf, srcA, zero);                           \
        KUNIT_EXPECT_EQ(test, pad.buf[0], '\0');                \
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);       \
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);      \
        memfunc(pad.buf + 1, srcB, zero + 1);                   \
        KUNIT_EXPECT_EQ(test, pad.buf[0], '\0');                \
        KUNIT_EXPECT_EQ(test, pad.buf[1], 'B');                 \
        KUNIT_EXPECT_EQ(test, pad.buf[2], '\0');                \
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);       \
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);      \
        memfunc(pad.buf, srcA, zero + 1);                       \
        KUNIT_EXPECT_EQ(test, pad.buf[0], 'A');                 \
        KUNIT_EXPECT_EQ(test, pad.buf[1], 'B');                 \
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);       \
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);      \
        memfunc(pad.buf, srcA, len - 1);                        \
        KUNIT_EXPECT_EQ(test, pad.buf[1], 'A');                 \
        KUNIT_EXPECT_EQ(test, pad.buf[len - 1], '\0');          \
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);       \
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);      \
        memfunc(pad.buf, srcA, len);                            \
        KUNIT_EXPECT_EQ(test, pad.buf[1], 'A');                 \
        KUNIT_EXPECT_EQ(test, pad.buf[len - 1], 'A');           \
        KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);              \
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);       \
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);      \
        memfunc(pad.buf, srcA, len + 1);                        \
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);       \
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);      \
        memfunc(pad.buf + 1, srcB, len);                        \
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);       \
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);      \
                                                                \
        /* Reset error counter. */                              \
        fortify_write_overflows = 0;                            \
        /* Copy nothing into nothing: no errors. */             \
        memfunc(empty.buf, srcB, zero);                         \
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);       \
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);      \
        memfunc(empty.buf, srcB, zero + 1);                     \
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);       \
        KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);      \
}
__fortify_test(memcpy)
__fortify_test(memmove)

static void fortify_test_memscan(struct kunit *test)
{
        char haystack[] = "Where oh where is my memory range?";
        char *mem = haystack + strlen("Where oh where is ");
        char needle = 'm';
        size_t len = sizeof(haystack);

        OPTIMIZER_HIDE_VAR(len);

        KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len),
                                  mem);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        /* Catch too-large range. */
        KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len + 1),
                                  NULL);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
        KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len * 2),
                                  NULL);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void fortify_test_memchr(struct kunit *test)
{
        char haystack[] = "Where oh where is my memory range?";
        char *mem = haystack + strlen("Where oh where is ");
        char needle = 'm';
        size_t len = sizeof(haystack);

        OPTIMIZER_HIDE_VAR(len);

        KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len),
                                  mem);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        /* Catch too-large range. */
        KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len + 1),
                                  NULL);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
        KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len * 2),
                                  NULL);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void fortify_test_memchr_inv(struct kunit *test)
{
        char haystack[] = "Where oh where is my memory range?";
        char *mem = haystack + 1;
        char needle = 'W';
        size_t len = sizeof(haystack);

        OPTIMIZER_HIDE_VAR(len);

        /* Normal search is okay. */
        KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len),
                                  mem);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        /* Catch too-large range. */
        KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len + 1),
                                  NULL);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
        KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len * 2),
                                  NULL);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void fortify_test_memcmp(struct kunit *test)
{
        char one[] = "My mind is going ...";
        char two[] = "My mind is going ... I can feel it.";
        volatile size_t one_len = sizeof(one) - 1;
        volatile size_t two_len = sizeof(two) - 1;

        OPTIMIZER_HIDE_VAR(one_len);
        OPTIMIZER_HIDE_VAR(two_len);

        /* We match the first string (ignoring the %NUL). */
        KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len), 0);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        /* Still in bounds, but no longer matching. */
        KUNIT_ASSERT_LT(test, memcmp(one, two, one_len + 1), 0);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);

        /* Catch too-large ranges. */
        KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len + 2), INT_MIN);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);

        KUNIT_ASSERT_EQ(test, memcmp(two, one, two_len + 2), INT_MIN);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void fortify_test_kmemdup(struct kunit *test)
{
        char src[] = "I got Doom running on it!";
        char *copy;
        size_t len = sizeof(src);

        OPTIMIZER_HIDE_VAR(len);

        /* Copy is within bounds. */
        copy = kmemdup(src, len, GFP_KERNEL);
        KUNIT_EXPECT_NOT_NULL(test, copy);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        kfree(copy);

        /* Without %NUL. */
        copy = kmemdup(src, len - 1, GFP_KERNEL);
        KUNIT_EXPECT_NOT_NULL(test, copy);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        kfree(copy);

        /* Tiny bounds. */
        copy = kmemdup(src, 1, GFP_KERNEL);
        KUNIT_EXPECT_NOT_NULL(test, copy);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
        kfree(copy);

        /* Out of bounds by 1 byte. */
        copy = kmemdup(src, len + 1, GFP_KERNEL);
        KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
        kfree(copy);

        /* Way out of bounds. */
        copy = kmemdup(src, len * 2, GFP_KERNEL);
        KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
        kfree(copy);

        /* Starting offset causing out of bounds. */
        copy = kmemdup(src + 1, len, GFP_KERNEL);
        KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR);
        KUNIT_EXPECT_EQ(test, fortify_read_overflows, 3);
        kfree(copy);
}

static int fortify_test_init(struct kunit *test)
{
        if (!IS_ENABLED(CONFIG_FORTIFY_SOURCE))
                kunit_skip(test, "Not built with CONFIG_FORTIFY_SOURCE=y");

        fortify_read_overflows = 0;
        kunit_add_named_resource(test, NULL, NULL, &read_resource,
                                 "fortify_read_overflows",
                                 &fortify_read_overflows);
        fortify_write_overflows = 0;
        kunit_add_named_resource(test, NULL, NULL, &write_resource,
                                 "fortify_write_overflows",
                                 &fortify_write_overflows);
        return 0;
}

static struct kunit_case fortify_test_cases[] = {
        KUNIT_CASE(fortify_test_known_sizes),
        KUNIT_CASE(fortify_test_control_flow_split),
        KUNIT_CASE(fortify_test_alloc_size_kmalloc_const),
        KUNIT_CASE(fortify_test_alloc_size_kmalloc_dynamic),
        KUNIT_CASE(fortify_test_alloc_size_vmalloc_const),
        KUNIT_CASE(fortify_test_alloc_size_vmalloc_dynamic),
        KUNIT_CASE(fortify_test_alloc_size_kvmalloc_const),
        KUNIT_CASE(fortify_test_alloc_size_kvmalloc_dynamic),
        KUNIT_CASE(fortify_test_alloc_size_devm_kmalloc_const),
        KUNIT_CASE(fortify_test_alloc_size_devm_kmalloc_dynamic),
        KUNIT_CASE(fortify_test_realloc_size),
        KUNIT_CASE(fortify_test_strlen),
        KUNIT_CASE(fortify_test_strnlen),
        KUNIT_CASE(fortify_test_strcpy),
        KUNIT_CASE(fortify_test_strncpy),
        KUNIT_CASE(fortify_test_strscpy),
        KUNIT_CASE(fortify_test_strcat),
        KUNIT_CASE(fortify_test_strncat),
        KUNIT_CASE(fortify_test_strlcat),
        /* skip memset: performs bounds checking on whole structs */
        KUNIT_CASE(fortify_test_memcpy),
        KUNIT_CASE(fortify_test_memmove),
        KUNIT_CASE(fortify_test_memscan),
        KUNIT_CASE(fortify_test_memchr),
        KUNIT_CASE(fortify_test_memchr_inv),
        KUNIT_CASE(fortify_test_memcmp),
        KUNIT_CASE(fortify_test_kmemdup),
        {}
};

static struct kunit_suite fortify_test_suite = {
        .name = "fortify",
        .init = fortify_test_init,
        .test_cases = fortify_test_cases,
};

kunit_test_suite(fortify_test_suite);

MODULE_DESCRIPTION("Runtime test cases for CONFIG_FORTIFY_SOURCE");
MODULE_LICENSE("GPL");