// SPDX-License-Identifier: GPL-2.0
/*
 * Test cases for KFENCE memory safety error detector. Since the interface with
 * which KFENCE's reports are obtained is via the console, this is the output we
 * should verify. For each test case checks the presence (or absence) of
 * generated reports. Relies on 'console' tracepoint to capture reports as they
 * appear in the kernel log.
 *
 * Copyright (C) 2020, Google LLC.
 * Author: Alexander Potapenko <glider@google.com>
 *         Marco Elver <elver@google.com>
 */

#include <kunit/test.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kfence.h>
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/string_choices.h>
#include <linux/tracepoint.h>
#include <trace/events/printk.h>

#include <asm/kfence.h>

#include "kfence.h"

/* May be overridden by <asm/kfence.h>. */
#ifndef arch_kfence_test_address
#define arch_kfence_test_address(addr) (addr)
#endif

#define KFENCE_TEST_REQUIRES(test, cond) do {                   \
        if (!(cond))                                            \
                kunit_skip((test), "Test requires: " #cond);    \
} while (0)

/* Report as observed from console. */
static struct {
        spinlock_t lock;
        int nlines;
        char lines[2][256];
} observed = {
        .lock = __SPIN_LOCK_UNLOCKED(observed.lock),
};

/* Probe for console output: obtains observed lines of interest. */
static void probe_console(void *ignore, const char *buf, size_t len)
{
        unsigned long flags;
        int nlines;

        spin_lock_irqsave(&observed.lock, flags);
        nlines = observed.nlines;

        if (strnstr(buf, "BUG: KFENCE: ", len) && strnstr(buf, "test_", len)) {
                /*
                 * KFENCE report and related to the test.
                 *
                 * The provided @buf is not NUL-terminated; copy no more than
                 * @len bytes and let strscpy() add the missing NUL-terminator.
                 */
                strscpy(observed.lines[0], buf, min(len + 1, sizeof(observed.lines[0])));
                nlines = 1;
        } else if (nlines == 1 && (strnstr(buf, "at 0x", len) || strnstr(buf, "of 0x", len))) {
                strscpy(observed.lines[nlines++], buf, min(len + 1, sizeof(observed.lines[0])));
        }

        WRITE_ONCE(observed.nlines, nlines); /* Publish new nlines. */
        spin_unlock_irqrestore(&observed.lock, flags);
}

/* Check if a report related to the test exists. */
static bool report_available(void)
{
        return READ_ONCE(observed.nlines) == ARRAY_SIZE(observed.lines);
}

/* Information we expect in a report. */
struct expect_report {
        enum kfence_error_type type; /* The type or error. */
        void *fn; /* Function pointer to expected function where access occurred. */
        char *addr; /* Address at which the bad access occurred. */
        bool is_write; /* Is access a write. */
};

static const char *get_access_type(const struct expect_report *r)
{
        return str_write_read(r->is_write);
}

/* Check observed report matches information in @r. */
static bool report_matches(const struct expect_report *r)
{
        unsigned long addr = (unsigned long)r->addr;
        bool ret = false;
        unsigned long flags;
        typeof(observed.lines) expect;
        const char *end;
        char *cur;

        /* Doubled-checked locking. */
        if (!report_available())
                return false;

        /* Generate expected report contents. */

        /* Title */
        cur = expect[0];
        end = ARRAY_END(expect[0]);
        switch (r->type) {
        case KFENCE_ERROR_OOB:
                cur += scnprintf(cur, end - cur, "BUG: KFENCE: out-of-bounds %s",
                                 get_access_type(r));
                break;
        case KFENCE_ERROR_UAF:
                cur += scnprintf(cur, end - cur, "BUG: KFENCE: use-after-free %s",
                                 get_access_type(r));
                break;
        case KFENCE_ERROR_CORRUPTION:
                cur += scnprintf(cur, end - cur, "BUG: KFENCE: memory corruption");
                break;
        case KFENCE_ERROR_INVALID:
                cur += scnprintf(cur, end - cur, "BUG: KFENCE: invalid %s",
                                 get_access_type(r));
                break;
        case KFENCE_ERROR_INVALID_FREE:
                cur += scnprintf(cur, end - cur, "BUG: KFENCE: invalid free");
                break;
        }

        scnprintf(cur, end - cur, " in %pS", r->fn);
        /* The exact offset won't match, remove it; also strip module name. */
        cur = strchr(expect[0], '+');
        if (cur)
                *cur = '\0';

        /* Access information */
        cur = expect[1];
        end = ARRAY_END(expect[1]);

        switch (r->type) {
        case KFENCE_ERROR_OOB:
                cur += scnprintf(cur, end - cur, "Out-of-bounds %s at", get_access_type(r));
                addr = arch_kfence_test_address(addr);
                break;
        case KFENCE_ERROR_UAF:
                cur += scnprintf(cur, end - cur, "Use-after-free %s at", get_access_type(r));
                addr = arch_kfence_test_address(addr);
                break;
        case KFENCE_ERROR_CORRUPTION:
                cur += scnprintf(cur, end - cur, "Corrupted memory at");
                break;
        case KFENCE_ERROR_INVALID:
                cur += scnprintf(cur, end - cur, "Invalid %s at", get_access_type(r));
                addr = arch_kfence_test_address(addr);
                break;
        case KFENCE_ERROR_INVALID_FREE:
                cur += scnprintf(cur, end - cur, "Invalid free of");
                break;
        }

        cur += scnprintf(cur, end - cur, " 0x%p", (void *)addr);

        spin_lock_irqsave(&observed.lock, flags);
        if (!report_available())
                goto out; /* A new report is being captured. */

        /* Finally match expected output to what we actually observed. */
        ret = strstr(observed.lines[0], expect[0]) && strstr(observed.lines[1], expect[1]);
out:
        spin_unlock_irqrestore(&observed.lock, flags);
        return ret;
}

/* ===== Test cases ===== */

#define TEST_PRIV_WANT_MEMCACHE ((void *)1)

/* Cache used by tests; if NULL, allocate from kmalloc instead. */
static struct kmem_cache *test_cache;

static size_t setup_test_cache(struct kunit *test, size_t size, slab_flags_t flags,
                               void (*ctor)(void *))
{
        if (test->priv != TEST_PRIV_WANT_MEMCACHE)
                return size;

        kunit_info(test, "%s: size=%zu, ctor=%ps\n", __func__, size, ctor);

        /*
         * Use SLAB_NO_MERGE to prevent merging with existing caches.
         * Use SLAB_ACCOUNT to allocate via memcg, if enabled.
         */
        flags |= SLAB_NO_MERGE | SLAB_ACCOUNT;
        test_cache = kmem_cache_create("test", size, 1, flags, ctor);
        KUNIT_ASSERT_TRUE_MSG(test, test_cache, "could not create cache");

        return size;
}

static void test_cache_destroy(void)
{
        if (!test_cache)
                return;

        kmem_cache_destroy(test_cache);
        test_cache = NULL;
}

static inline size_t kmalloc_cache_alignment(size_t size)
{
        /* just to get ->align so no need to pass in the real caller */
        enum kmalloc_cache_type type = kmalloc_type(GFP_KERNEL, 0);
        return kmalloc_caches[type][__kmalloc_index(size, false)]->align;
}

/* Must always inline to match stack trace against caller. */
static __always_inline void test_free(void *ptr)
{
        if (test_cache)
                kmem_cache_free(test_cache, ptr);
        else
                kfree(ptr);
}

/*
 * If this should be a KFENCE allocation, and on which side the allocation and
 * the closest guard page should be.
 */
enum allocation_policy {
        ALLOCATE_ANY, /* KFENCE, any side. */
        ALLOCATE_LEFT, /* KFENCE, left side of page. */
        ALLOCATE_RIGHT, /* KFENCE, right side of page. */
        ALLOCATE_NONE, /* No KFENCE allocation. */
};

/*
 * Try to get a guarded allocation from KFENCE. Uses either kmalloc() or the
 * current test_cache if set up.
 */
static void *test_alloc(struct kunit *test, size_t size, gfp_t gfp, enum allocation_policy policy)
{
        void *alloc;
        unsigned long timeout, resched_after;
        const char *policy_name;

        switch (policy) {
        case ALLOCATE_ANY:
                policy_name = "any";
                break;
        case ALLOCATE_LEFT:
                policy_name = "left";
                break;
        case ALLOCATE_RIGHT:
                policy_name = "right";
                break;
        case ALLOCATE_NONE:
                policy_name = "none";
                break;
        }

        kunit_info(test, "%s: size=%zu, gfp=%x, policy=%s, cache=%i\n", __func__, size, gfp,
                   policy_name, !!test_cache);

        /*
         * 100x the sample interval should be more than enough to ensure we get
         * a KFENCE allocation eventually.
         */
        timeout = jiffies + msecs_to_jiffies(100 * kfence_sample_interval);
        /*
         * Especially for non-preemption kernels, ensure the allocation-gate
         * timer can catch up: after @resched_after, every failed allocation
         * attempt yields, to ensure the allocation-gate timer is scheduled.
         */
        resched_after = jiffies + msecs_to_jiffies(kfence_sample_interval);
        do {
                if (test_cache)
                        alloc = kmem_cache_alloc(test_cache, gfp);
                else
                        alloc = kmalloc(size, gfp);

                if (is_kfence_address(alloc)) {
                        struct slab *slab = virt_to_slab(alloc);
                        enum kmalloc_cache_type type = kmalloc_type(GFP_KERNEL, _RET_IP_);
                        struct kmem_cache *s = test_cache ?:
                                        kmalloc_caches[type][__kmalloc_index(size, false)];

                        /*
                         * Verify that various helpers return the right values
                         * even for KFENCE objects; these are required so that
                         * memcg accounting works correctly.
                         */
                        KUNIT_EXPECT_EQ(test, obj_to_index(s, slab, alloc), 0U);
                        KUNIT_EXPECT_EQ(test, objs_per_slab(s, slab), 1);

                        if (policy == ALLOCATE_ANY)
                                return alloc;
                        if (policy == ALLOCATE_LEFT && PAGE_ALIGNED(alloc))
                                return alloc;
                        if (policy == ALLOCATE_RIGHT && !PAGE_ALIGNED(alloc))
                                return alloc;
                } else if (policy == ALLOCATE_NONE)
                        return alloc;

                test_free(alloc);

                if (time_after(jiffies, resched_after))
                        cond_resched();
        } while (time_before(jiffies, timeout));

        KUNIT_ASSERT_TRUE_MSG(test, false, "failed to allocate from KFENCE");
        return NULL; /* Unreachable. */
}

static void test_out_of_bounds_read(struct kunit *test)
{
        size_t size = 32;
        struct expect_report expect = {
                .type = KFENCE_ERROR_OOB,
                .fn = test_out_of_bounds_read,
                .is_write = false,
        };
        char *buf;

        setup_test_cache(test, size, 0, NULL);

        /*
         * If we don't have our own cache, adjust based on alignment, so that we
         * actually access guard pages on either side.
         */
        if (!test_cache)
                size = kmalloc_cache_alignment(size);

        /* Test both sides. */

        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_LEFT);
        expect.addr = buf - 1;
        READ_ONCE(*expect.addr);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
        test_free(buf);

        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT);
        expect.addr = buf + size;
        READ_ONCE(*expect.addr);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
        test_free(buf);
}

static void test_out_of_bounds_write(struct kunit *test)
{
        size_t size = 32;
        struct expect_report expect = {
                .type = KFENCE_ERROR_OOB,
                .fn = test_out_of_bounds_write,
                .is_write = true,
        };
        char *buf;

        setup_test_cache(test, size, 0, NULL);
        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_LEFT);
        expect.addr = buf - 1;
        WRITE_ONCE(*expect.addr, 42);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
        test_free(buf);
}

static void test_use_after_free_read(struct kunit *test)
{
        const size_t size = 32;
        struct expect_report expect = {
                .type = KFENCE_ERROR_UAF,
                .fn = test_use_after_free_read,
                .is_write = false,
        };

        setup_test_cache(test, size, 0, NULL);
        expect.addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
        test_free(expect.addr);
        READ_ONCE(*expect.addr);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}

static void test_use_after_free_read_nofault(struct kunit *test)
{
        const size_t size = 32;
        char *addr;
        char dst;
        int ret;

        setup_test_cache(test, size, 0, NULL);
        addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
        test_free(addr);
        /* Use after free with *_nofault() */
        ret = copy_from_kernel_nofault(&dst, addr, 1);
        KUNIT_EXPECT_EQ(test, ret, -EFAULT);
        KUNIT_EXPECT_FALSE(test, report_available());
}

static void test_double_free(struct kunit *test)
{
        const size_t size = 32;
        struct expect_report expect = {
                .type = KFENCE_ERROR_INVALID_FREE,
                .fn = test_double_free,
        };

        setup_test_cache(test, size, 0, NULL);
        expect.addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
        test_free(expect.addr);
        test_free(expect.addr); /* Double-free. */
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}

static void test_invalid_addr_free(struct kunit *test)
{
        const size_t size = 32;
        struct expect_report expect = {
                .type = KFENCE_ERROR_INVALID_FREE,
                .fn = test_invalid_addr_free,
        };
        char *buf;

        setup_test_cache(test, size, 0, NULL);
        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
        expect.addr = buf + 1; /* Free on invalid address. */
        test_free(expect.addr); /* Invalid address free. */
        test_free(buf); /* No error. */
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}

static void test_corruption(struct kunit *test)
{
        size_t size = 32;
        struct expect_report expect = {
                .type = KFENCE_ERROR_CORRUPTION,
                .fn = test_corruption,
        };
        char *buf;

        setup_test_cache(test, size, 0, NULL);

        /* Test both sides. */

        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_LEFT);
        expect.addr = buf + size;
        WRITE_ONCE(*expect.addr, 42);
        test_free(buf);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));

        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT);
        expect.addr = buf - 1;
        WRITE_ONCE(*expect.addr, 42);
        test_free(buf);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}

/*
 * KFENCE is unable to detect an OOB if the allocation's alignment requirements
 * leave a gap between the object and the guard page. Specifically, an
 * allocation of e.g. 73 bytes is aligned on 8 and 128 bytes for SLUB or SLAB
 * respectively. Therefore it is impossible for the allocated object to
 * contiguously line up with the right guard page.
 *
 * However, we test that an access to memory beyond the gap results in KFENCE
 * detecting an OOB access.
 */
static void test_kmalloc_aligned_oob_read(struct kunit *test)
{
        const size_t size = 73;
        const size_t align = kmalloc_cache_alignment(size);
        struct expect_report expect = {
                .type = KFENCE_ERROR_OOB,
                .fn = test_kmalloc_aligned_oob_read,
                .is_write = false,
        };
        char *buf;

        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT);

        /*
         * The object is offset to the right, so there won't be an OOB to the
         * left of it.
         */
        READ_ONCE(*(buf - 1));
        KUNIT_EXPECT_FALSE(test, report_available());

        /*
         * @buf must be aligned on @align, therefore buf + size belongs to the
         * same page -> no OOB.
         */
        READ_ONCE(*(buf + size));
        KUNIT_EXPECT_FALSE(test, report_available());

        /* Overflowing by @align bytes will result in an OOB. */
        expect.addr = buf + size + align;
        READ_ONCE(*expect.addr);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));

        test_free(buf);
}

static void test_kmalloc_aligned_oob_write(struct kunit *test)
{
        const size_t size = 73;
        struct expect_report expect = {
                .type = KFENCE_ERROR_CORRUPTION,
                .fn = test_kmalloc_aligned_oob_write,
        };
        char *buf;

        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT);
        /*
         * The object is offset to the right, so we won't get a page
         * fault immediately after it.
         */
        expect.addr = buf + size;
        WRITE_ONCE(*expect.addr, READ_ONCE(*expect.addr) + 1);
        KUNIT_EXPECT_FALSE(test, report_available());
        test_free(buf);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}

/* Test cache shrinking and destroying with KFENCE. */
static void test_shrink_memcache(struct kunit *test)
{
        const size_t size = 32;
        void *buf;

        setup_test_cache(test, size, 0, NULL);
        KUNIT_EXPECT_TRUE(test, test_cache);
        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
        kmem_cache_shrink(test_cache);
        test_free(buf);

        KUNIT_EXPECT_FALSE(test, report_available());
}

static void ctor_set_x(void *obj)
{
        /* Every object has at least 8 bytes. */
        memset(obj, 'x', 8);
}

/* Ensure that SL*B does not modify KFENCE objects on bulk free. */
static void test_free_bulk(struct kunit *test)
{
        int iter;

        for (iter = 0; iter < 5; iter++) {
                const size_t size = setup_test_cache(test, get_random_u32_inclusive(8, 307),
                                                     0, (iter & 1) ? ctor_set_x : NULL);
                void *objects[] = {
                        test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT),
                        test_alloc(test, size, GFP_KERNEL, ALLOCATE_NONE),
                        test_alloc(test, size, GFP_KERNEL, ALLOCATE_LEFT),
                        test_alloc(test, size, GFP_KERNEL, ALLOCATE_NONE),
                        test_alloc(test, size, GFP_KERNEL, ALLOCATE_NONE),
                };

                kmem_cache_free_bulk(test_cache, ARRAY_SIZE(objects), objects);
                KUNIT_ASSERT_FALSE(test, report_available());
                test_cache_destroy();
        }
}

/* Test init-on-free works. */
static void test_init_on_free(struct kunit *test)
{
        const size_t size = 32;
        struct expect_report expect = {
                .type = KFENCE_ERROR_UAF,
                .fn = test_init_on_free,
                .is_write = false,
        };
        int i;

        KFENCE_TEST_REQUIRES(test, IS_ENABLED(CONFIG_INIT_ON_FREE_DEFAULT_ON));
        /* Assume it hasn't been disabled on command line. */

        setup_test_cache(test, size, 0, NULL);
        expect.addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
        for (i = 0; i < size; i++)
                expect.addr[i] = i + 1;
        test_free(expect.addr);

        for (i = 0; i < size; i++) {
                /*
                 * This may fail if the page was recycled by KFENCE and then
                 * written to again -- this however, is near impossible with a
                 * default config.
                 */
                KUNIT_EXPECT_EQ(test, expect.addr[i], (char)0);

                if (!i) /* Only check first access to not fail test if page is ever re-protected. */
                        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
        }
}

/* Ensure that constructors work properly. */
static void test_memcache_ctor(struct kunit *test)
{
        const size_t size = 32;
        char *buf;
        int i;

        setup_test_cache(test, size, 0, ctor_set_x);
        buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);

        for (i = 0; i < 8; i++)
                KUNIT_EXPECT_EQ(test, buf[i], (char)'x');

        test_free(buf);

        KUNIT_EXPECT_FALSE(test, report_available());
}

/* Test that memory is zeroed if requested. */
static void test_gfpzero(struct kunit *test)
{
        const size_t size = PAGE_SIZE; /* PAGE_SIZE so we can use ALLOCATE_ANY. */
        char *buf1, *buf2;
        int i;

        /* Skip if we think it'd take too long. */
        KFENCE_TEST_REQUIRES(test, kfence_sample_interval <= 100);

        setup_test_cache(test, size, 0, NULL);
        buf1 = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
        for (i = 0; i < size; i++)
                buf1[i] = i + 1;
        test_free(buf1);

        /* Try to get same address again -- this can take a while. */
        for (i = 0;; i++) {
                buf2 = test_alloc(test, size, GFP_KERNEL | __GFP_ZERO, ALLOCATE_ANY);
                if (buf1 == buf2)
                        break;
                test_free(buf2);

                if (kthread_should_stop() || (i == CONFIG_KFENCE_NUM_OBJECTS)) {
                        kunit_warn(test, "giving up ... cannot get same object back\n");
                        return;
                }
                cond_resched();
        }

        for (i = 0; i < size; i++)
                KUNIT_EXPECT_EQ(test, buf2[i], (char)0);

        test_free(buf2);

        KUNIT_EXPECT_FALSE(test, report_available());
}

static void test_invalid_access(struct kunit *test)
{
        const struct expect_report expect = {
                .type = KFENCE_ERROR_INVALID,
                .fn = test_invalid_access,
                .addr = &__kfence_pool[10],
                .is_write = false,
        };

        READ_ONCE(__kfence_pool[10]);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}

/* Test SLAB_TYPESAFE_BY_RCU works. */
static void test_memcache_typesafe_by_rcu(struct kunit *test)
{
        const size_t size = 32;
        struct expect_report expect = {
                .type = KFENCE_ERROR_UAF,
                .fn = test_memcache_typesafe_by_rcu,
                .is_write = false,
        };

        setup_test_cache(test, size, SLAB_TYPESAFE_BY_RCU, NULL);
        KUNIT_EXPECT_TRUE(test, test_cache); /* Want memcache. */

        expect.addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
        *expect.addr = 42;

        rcu_read_lock();
        test_free(expect.addr);
        KUNIT_EXPECT_EQ(test, *expect.addr, (char)42);
        /*
         * Up to this point, memory should not have been freed yet, and
         * therefore there should be no KFENCE report from the above access.
         */
        rcu_read_unlock();

        /* Above access to @expect.addr should not have generated a report! */
        KUNIT_EXPECT_FALSE(test, report_available());

        /* Only after rcu_barrier() is the memory guaranteed to be freed. */
        rcu_barrier();

        /* Expect use-after-free. */
        KUNIT_EXPECT_EQ(test, *expect.addr, (char)42);
        KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}

/* Test krealloc(). */
static void test_krealloc(struct kunit *test)
{
        const size_t size = 32;
        const struct expect_report expect = {
                .type = KFENCE_ERROR_UAF,
                .fn = test_krealloc,
                .addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY),
                .is_write = false,
        };
        char *buf = expect.addr;
        int i;

        KUNIT_EXPECT_FALSE(test, test_cache);
        KUNIT_EXPECT_EQ(test, ksize(buf), size); /* Precise size match after KFENCE alloc. */
        for (i = 0; i < size; i++)
                buf[i] = i + 1;

        /* Check that we successfully change the size. */
        buf = krealloc(buf, size * 3, GFP_KERNEL); /* Grow. */
        /* Note: Might no longer be a KFENCE alloc. */
        KUNIT_EXPECT_GE(test, ksize(buf), size * 3);
        for (i = 0; i < size; i++)
                KUNIT_EXPECT_EQ(test, buf[i], (char)(i + 1));
        for (; i < size * 3; i++) /* Fill to extra bytes. */
                buf[i] = i + 1;

        buf = krealloc(buf, size * 2, GFP_KERNEL); /* Shrink. */
        KUNIT_EXPECT_GE(test, ksize(buf), size * 2);
        for (i = 0; i < size * 2; i++)
                KUNIT_EXPECT_EQ(test, buf[i], (char)(i + 1));

        buf = krealloc(buf, 0, GFP_KERNEL); /* Free. */
        KUNIT_EXPECT_EQ(test, (unsigned long)buf, (unsigned long)ZERO_SIZE_PTR);
        KUNIT_ASSERT_FALSE(test, report_available()); /* No reports yet! */

        READ_ONCE(*expect.addr); /* Ensure krealloc() actually freed earlier KFENCE object. */
        KUNIT_ASSERT_TRUE(test, report_matches(&expect));
}

/* Test that some objects from a bulk allocation belong to KFENCE pool. */
static void test_memcache_alloc_bulk(struct kunit *test)
{
        const size_t size = 32;
        bool pass = false;
        unsigned long timeout;

        setup_test_cache(test, size, 0, NULL);
        KUNIT_EXPECT_TRUE(test, test_cache); /* Want memcache. */
        /*
         * 100x the sample interval should be more than enough to ensure we get
         * a KFENCE allocation eventually.
         */
        timeout = jiffies + msecs_to_jiffies(100 * kfence_sample_interval);
        do {
                void *objects[100];
                int i, num = kmem_cache_alloc_bulk(test_cache, GFP_ATOMIC, ARRAY_SIZE(objects),
                                                   objects);
                if (!num)
                        continue;
                for (i = 0; i < ARRAY_SIZE(objects); i++) {
                        if (is_kfence_address(objects[i])) {
                                pass = true;
                                break;
                        }
                }
                kmem_cache_free_bulk(test_cache, num, objects);
                /*
                 * kmem_cache_alloc_bulk() disables interrupts, and calling it
                 * in a tight loop may not give KFENCE a chance to switch the
                 * static branch. Call cond_resched() to let KFENCE chime in.
                 */
                cond_resched();
        } while (!pass && time_before(jiffies, timeout));

        KUNIT_EXPECT_TRUE(test, pass);
        KUNIT_EXPECT_FALSE(test, report_available());
}

/*
 * KUnit does not provide a way to provide arguments to tests, and we encode
 * additional info in the name. Set up 2 tests per test case, one using the
 * default allocator, and another using a custom memcache (suffix '-memcache').
 */
#define KFENCE_KUNIT_CASE(test_name)                                            \
        { .run_case = test_name, .name = #test_name },                          \
        { .run_case = test_name, .name = #test_name "-memcache" }

static struct kunit_case kfence_test_cases[] = {
        KFENCE_KUNIT_CASE(test_out_of_bounds_read),
        KFENCE_KUNIT_CASE(test_out_of_bounds_write),
        KFENCE_KUNIT_CASE(test_use_after_free_read),
        KFENCE_KUNIT_CASE(test_use_after_free_read_nofault),
        KFENCE_KUNIT_CASE(test_double_free),
        KFENCE_KUNIT_CASE(test_invalid_addr_free),
        KFENCE_KUNIT_CASE(test_corruption),
        KFENCE_KUNIT_CASE(test_free_bulk),
        KFENCE_KUNIT_CASE(test_init_on_free),
        KUNIT_CASE(test_kmalloc_aligned_oob_read),
        KUNIT_CASE(test_kmalloc_aligned_oob_write),
        KUNIT_CASE(test_shrink_memcache),
        KUNIT_CASE(test_memcache_ctor),
        KUNIT_CASE(test_invalid_access),
        KUNIT_CASE(test_gfpzero),
        KUNIT_CASE(test_memcache_typesafe_by_rcu),
        KUNIT_CASE(test_krealloc),
        KUNIT_CASE(test_memcache_alloc_bulk),
        {},
};

/* ===== End test cases ===== */

static int test_init(struct kunit *test)
{
        unsigned long flags;
        int i;

        if (!__kfence_pool)
                return -EINVAL;

        spin_lock_irqsave(&observed.lock, flags);
        for (i = 0; i < ARRAY_SIZE(observed.lines); i++)
                observed.lines[i][0] = '\0';
        observed.nlines = 0;
        spin_unlock_irqrestore(&observed.lock, flags);

        /* Any test with 'memcache' in its name will want a memcache. */
        if (strstr(test->name, "memcache"))
                test->priv = TEST_PRIV_WANT_MEMCACHE;
        else
                test->priv = NULL;

        return 0;
}

static void test_exit(struct kunit *test)
{
        test_cache_destroy();
}

static int kfence_suite_init(struct kunit_suite *suite)
{
        register_trace_console(probe_console, NULL);
        return 0;
}

static void kfence_suite_exit(struct kunit_suite *suite)
{
        unregister_trace_console(probe_console, NULL);
        tracepoint_synchronize_unregister();
}

static struct kunit_suite kfence_test_suite = {
        .name = "kfence",
        .test_cases = kfence_test_cases,
        .init = test_init,
        .exit = test_exit,
        .suite_init = kfence_suite_init,
        .suite_exit = kfence_suite_exit,
};

kunit_test_suites(&kfence_test_suite);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Alexander Potapenko <glider@google.com>, Marco Elver <elver@google.com>");
MODULE_DESCRIPTION("kfence unit test suite");