// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Test cases for compiler-based stack variable zeroing via
 * -ftrivial-auto-var-init={zero,pattern}.
 * For example, see:
 * "Running tests with kunit_tool" at Documentation/dev-tools/kunit/start.rst
 *      ./tools/testing/kunit/kunit.py run stackinit [--raw_output] \
 *              --make_option LLVM=1 \
 *              --kconfig_add CONFIG_INIT_STACK_ALL_ZERO=y
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <kunit/test.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>

/* Exfiltration buffer. */
#define MAX_VAR_SIZE    128
static u8 check_buf[MAX_VAR_SIZE];

/* Character array to trigger stack protector in all functions. */
#define VAR_BUFFER       32

/* Volatile mask to convince compiler to copy memory with 0xff. */
static volatile u8 forced_mask = 0xff;

/* Location and size tracking to validate fill and test are colocated. */
static void *fill_start, *target_start;
static size_t fill_size, target_size;

static bool stackinit_range_contains(char *haystack_start, size_t haystack_size,
                                     char *needle_start, size_t needle_size)
{
        if (needle_start >= haystack_start &&
            needle_start + needle_size <= haystack_start + haystack_size)
                return true;
        return false;
}

/* Whether the test is expected to fail. */
#define WANT_SUCCESS                            0
#define XFAIL                                   1

#define DO_NOTHING_TYPE_SCALAR(var_type)        var_type
#define DO_NOTHING_TYPE_STRING(var_type)        void
#define DO_NOTHING_TYPE_STRUCT(var_type)        void
#define DO_NOTHING_TYPE_UNION(var_type)         void

#define DO_NOTHING_RETURN_SCALAR(ptr)           *(ptr)
#define DO_NOTHING_RETURN_STRING(ptr)           /**/
#define DO_NOTHING_RETURN_STRUCT(ptr)           /**/
#define DO_NOTHING_RETURN_UNION(ptr)            /**/

#define DO_NOTHING_CALL_SCALAR(var, name)                       \
                (var) = do_nothing_ ## name(&(var))
#define DO_NOTHING_CALL_STRING(var, name)                       \
                do_nothing_ ## name(var)
#define DO_NOTHING_CALL_STRUCT(var, name)                       \
                do_nothing_ ## name(&(var))
#define DO_NOTHING_CALL_UNION(var, name)                        \
                do_nothing_ ## name(&(var))

#define FETCH_ARG_SCALAR(var)           &var
#define FETCH_ARG_STRING(var)           var
#define FETCH_ARG_STRUCT(var)           &var
#define FETCH_ARG_UNION(var)            &var

/*
 * On m68k, if the leaf function test variable is longer than 8 bytes,
 * the start of the stack frame moves. 8 is sufficiently large to
 * test m68k char arrays, but leave it at 16 for other architectures.
 */
#ifdef CONFIG_M68K
#define FILL_SIZE_STRING                8
#define FILL_SIZE_ARRAY                 2
#else
#define FILL_SIZE_STRING                16
#define FILL_SIZE_ARRAY                 8
#endif

#define INIT_CLONE_SCALAR               /**/
#define INIT_CLONE_STRING               [FILL_SIZE_STRING]
#define INIT_CLONE_STRUCT               /**/
#define INIT_CLONE_UNION                /**/

#define ZERO_CLONE_SCALAR(zero)         memset(&(zero), 0x00, sizeof(zero))
#define ZERO_CLONE_STRING(zero)         memset(&(zero), 0x00, sizeof(zero))
/*
 * For the struct, intentionally poison padding to see if it gets
 * copied out in direct assignments.
 * */
#define ZERO_CLONE_STRUCT(zero)                         \
        do {                                            \
                memset(&(zero), 0xFF, sizeof(zero));    \
                zero.one = 0;                           \
                zero.two = 0;                           \
                zero.three = 0;                         \
                zero.four = 0;                          \
        } while (0)
#define ZERO_CLONE_UNION(zero)          ZERO_CLONE_STRUCT(zero)

#define INIT_SCALAR_none(var_type)      /**/
#define INIT_SCALAR_zero(var_type)      = 0

#define INIT_STRING_none(var_type)      [FILL_SIZE_STRING] /**/
#define INIT_STRING_zero(var_type)      [FILL_SIZE_STRING] = { }

#define INIT_STRUCT_none(var_type)      /**/
#define INIT_STRUCT_zero(var_type)      = { }
#define INIT_STRUCT_old_zero(var_type)  = { 0 }


#define __static_partial                { .two = 0, }
#define __static_all                    { .one = 0,                     \
                                          .two = 0,                     \
                                          .three = 0,                   \
                                          .four = 0,                    \
                                        }
#define __dynamic_partial               { .two = arg->two, }
#define __dynamic_all                   { .one = arg->one,              \
                                          .two = arg->two,              \
                                          .three = arg->three,          \
                                          .four = arg->four,            \
                                        }
#define __runtime_partial               var.two = 0
#define __runtime_all                   var.one = 0;                    \
                                        var.two = 0;                    \
                                        var.three = 0;                  \
                                        var.four = 0

#define INIT_STRUCT_static_partial(var_type)                            \
                                        = __static_partial
#define INIT_STRUCT_static_all(var_type)                                \
                                        = __static_all
#define INIT_STRUCT_dynamic_partial(var_type)                           \
                                        = __dynamic_partial
#define INIT_STRUCT_dynamic_all(var_type)                               \
                                        = __dynamic_all
#define INIT_STRUCT_runtime_partial(var_type)                           \
                                        ; __runtime_partial
#define INIT_STRUCT_runtime_all(var_type)                               \
                                        ; __runtime_all

#define INIT_STRUCT_assigned_static_partial(var_type)                   \
                                        ; var = (var_type)__static_partial
#define INIT_STRUCT_assigned_static_all(var_type)                       \
                                        ; var = (var_type)__static_all
#define INIT_STRUCT_assigned_dynamic_partial(var_type)                  \
                                        ; var = (var_type)__dynamic_partial
#define INIT_STRUCT_assigned_dynamic_all(var_type)                      \
                                        ; var = (var_type)__dynamic_all

#define INIT_STRUCT_assigned_copy(var_type)                             \
                                        ; var = *(arg)

/* Union initialization is the same as structs. */
#define INIT_UNION_none(var_type)       INIT_STRUCT_none(var_type)
#define INIT_UNION_zero(var_type)       INIT_STRUCT_zero(var_type)
#define INIT_UNION_old_zero(var_type)   INIT_STRUCT_old_zero(var_type)

#define INIT_UNION_static_partial(var_type)             \
        INIT_STRUCT_static_partial(var_type)
#define INIT_UNION_static_all(var_type)                 \
        INIT_STRUCT_static_all(var_type)
#define INIT_UNION_dynamic_partial(var_type)            \
        INIT_STRUCT_dynamic_partial(var_type)
#define INIT_UNION_dynamic_all(var_type)                \
        INIT_STRUCT_dynamic_all(var_type)
#define INIT_UNION_runtime_partial(var_type)            \
        INIT_STRUCT_runtime_partial(var_type)
#define INIT_UNION_runtime_all(var_type)                \
        INIT_STRUCT_runtime_all(var_type)
#define INIT_UNION_assigned_static_partial(var_type)    \
        INIT_STRUCT_assigned_static_partial(var_type)
#define INIT_UNION_assigned_static_all(var_type)        \
        INIT_STRUCT_assigned_static_all(var_type)
#define INIT_UNION_assigned_dynamic_partial(var_type)   \
        INIT_STRUCT_assigned_dynamic_partial(var_type)
#define INIT_UNION_assigned_dynamic_all(var_type)       \
        INIT_STRUCT_assigned_dynamic_all(var_type)
#define INIT_UNION_assigned_copy(var_type)              \
        INIT_STRUCT_assigned_copy(var_type)

/*
 * The "did we actually fill the stack?" check value needs
 * to be neither 0 nor any of the "pattern" bytes. The
 * pattern bytes are compiler, architecture, and type based,
 * so we have to pick a value that never appears for those
 * combinations. Use 0x99 which is not 0xFF, 0xFE, nor 0xAA.
 */
#define FILL_BYTE       0x99

/*
 * @name: unique string name for the test
 * @var_type: type to be tested for zeroing initialization
 * @which: is this a SCALAR, STRING, or STRUCT type?
 * @init_level: what kind of initialization is performed
 * @xfail: is this test expected to fail?
 */
#define DEFINE_TEST_DRIVER(name, var_type, which, xfail)        \
/* Returns 0 on success, 1 on failure. */                       \
static noinline void test_ ## name (struct kunit *test)         \
{                                                               \
        var_type zero INIT_CLONE_ ## which;                     \
        int ignored;                                            \
        u8 sum = 0, i;                                          \
                                                                \
        /* Notice when a new test is larger than expected. */   \
        BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE);              \
                                                                \
        /* Fill clone type with zero for per-field init. */     \
        ZERO_CLONE_ ## which(zero);                             \
        /* Clear entire check buffer for 0xFF overlap test. */  \
        memset(check_buf, 0x00, sizeof(check_buf));             \
        /* Fill stack with FILL_BYTE. */                        \
        ignored = leaf_ ##name((unsigned long)&ignored, 1,      \
                                FETCH_ARG_ ## which(zero));     \
        /* Verify all bytes overwritten with FILL_BYTE. */      \
        for (sum = 0, i = 0; i < target_size; i++)              \
                sum += (check_buf[i] != FILL_BYTE);             \
        /* Clear entire check buffer for later bit tests. */    \
        memset(check_buf, 0x00, sizeof(check_buf));             \
        /* Extract stack-defined variable contents. */          \
        ignored = leaf_ ##name((unsigned long)&ignored, 0,      \
                                FETCH_ARG_ ## which(zero));     \
        /*                                                      \
         * Delay the sum test to here to do as little as        \
         * possible between the two leaf function calls.        \
         */                                                     \
        KUNIT_ASSERT_EQ_MSG(test, sum, 0,                       \
                            "leaf fill was not 0x%02X!?\n",     \
                            FILL_BYTE);                         \
                                                                \
        /* Validate that compiler lined up fill and target. */  \
        KUNIT_ASSERT_TRUE_MSG(test,                             \
                stackinit_range_contains(fill_start, fill_size, \
                            target_start, target_size),         \
                "stackframe was not the same between calls!? "  \
                "(fill %zu wide, target offset by %d)\n",       \
                fill_size,                                      \
                (int)((ssize_t)(uintptr_t)fill_start -          \
                      (ssize_t)(uintptr_t)target_start));       \
                                                                \
        /* Validate check region has no FILL_BYTE bytes. */     \
        for (sum = 0, i = 0; i < target_size; i++)              \
                sum += (check_buf[i] == FILL_BYTE);             \
                                                                \
        if (sum != 0 && xfail)                                  \
                kunit_skip(test,                                \
                           "XFAIL uninit bytes: %d\n",          \
                           sum);                                \
        KUNIT_ASSERT_EQ_MSG(test, sum, 0,                       \
                "uninit bytes: %d\n", sum);                     \
}
#define DEFINE_TEST(name, var_type, which, init_level, xfail)   \
/* no-op to force compiler into ignoring "uninitialized" vars */\
static noinline DO_NOTHING_TYPE_ ## which(var_type)             \
do_nothing_ ## name(var_type *ptr)                              \
{                                                               \
        OPTIMIZER_HIDE_VAR(ptr);                                \
        /* Will always be true, but compiler doesn't know. */   \
        if ((unsigned long)ptr > 0x2)                           \
                return DO_NOTHING_RETURN_ ## which(ptr);        \
        else                                                    \
                return DO_NOTHING_RETURN_ ## which(ptr + 1);    \
}                                                               \
static noinline int leaf_ ## name(unsigned long sp, bool fill,  \
                                  var_type *arg)                \
{                                                               \
        char buf[VAR_BUFFER];                                   \
        var_type var                                            \
                INIT_ ## which ## _ ## init_level(var_type);    \
                                                                \
        target_start = &var;                                    \
        target_size = sizeof(var);                              \
        /*                                                      \
         * Keep this buffer around to make sure we've got a     \
         * stack frame of SOME kind...                          \
         */                                                     \
        memset(buf, (char)(sp & 0xff), sizeof(buf));            \
        /* Fill variable with FILL_BYTE. */                     \
        if (fill) {                                             \
                fill_start = &var;                              \
                fill_size = sizeof(var);                        \
                memset(fill_start,                              \
                       FILL_BYTE & forced_mask,                 \
                       fill_size);                              \
        }                                                       \
                                                                \
        /* Silence "never initialized" warnings. */             \
        DO_NOTHING_CALL_ ## which(var, name);                   \
                                                                \
        /* Exfiltrate "var". */                                 \
        memcpy(check_buf, target_start, target_size);           \
                                                                \
        return (int)buf[0] | (int)buf[sizeof(buf) - 1];         \
}                                                               \
DEFINE_TEST_DRIVER(name, var_type, which, xfail)

/* Structure with no padding. */
struct test_packed {
        unsigned long one;
        unsigned long two;
        unsigned long three;
        unsigned long four;
};

/* Simple structure with padding likely to be covered by compiler. */
struct test_small_hole {
        size_t one;
        char two;
        /* 3 byte padding hole here. */
        int three;
        unsigned long four;
};

/* Trigger unhandled padding in a structure. */
struct test_big_hole {
        u8 one;
        u8 two;
        u8 three;
        /* 61 byte padding hole here. */
        u8 four __aligned(64);
} __aligned(64);

struct test_trailing_hole {
        char *one;
        char *two;
        char *three;
        char four;
        /* "sizeof(unsigned long) - 1" byte padding hole here. */
};

/* Test if STRUCTLEAK is clearing structs with __user fields. */
struct test_user {
        u8 one;
        unsigned long two;
        char __user *three;
        unsigned long four;
};

/* No padding: all members are the same size. */
union test_same_sizes {
        unsigned long one;
        unsigned long two;
        unsigned long three;
        unsigned long four;
};

/* Mismatched sizes, with one and two being small */
union test_small_start {
        char one:1;
        char two;
        short three;
        unsigned long four;
        struct big_struct {
                unsigned long array[FILL_SIZE_ARRAY];
        } big;
};

/* Mismatched sizes, with three and four being small */
union test_small_end {
        short one;
        unsigned long two;
        char three:1;
        char four;
};

#define ALWAYS_PASS     WANT_SUCCESS
#define ALWAYS_FAIL     XFAIL

#ifdef CONFIG_INIT_STACK_NONE
# define USER_PASS      XFAIL
# define BYREF_PASS     XFAIL
# define STRONG_PASS    XFAIL
#else
# define USER_PASS      WANT_SUCCESS
# define BYREF_PASS     WANT_SUCCESS
# define STRONG_PASS    WANT_SUCCESS
#endif

#define DEFINE_SCALAR_TEST(name, init, xfail)                   \
                DEFINE_TEST(name ## _ ## init, name, SCALAR,    \
                            init, xfail)

#define DEFINE_SCALAR_TESTS(init, xfail)                        \
                DEFINE_SCALAR_TEST(u8, init, xfail);            \
                DEFINE_SCALAR_TEST(u16, init, xfail);           \
                DEFINE_SCALAR_TEST(u32, init, xfail);           \
                DEFINE_SCALAR_TEST(u64, init, xfail);           \
                DEFINE_TEST(char_array_ ## init, unsigned char, \
                            STRING, init, xfail)

#define DEFINE_STRUCT_TEST(name, init, xfail)                   \
                DEFINE_TEST(name ## _ ## init,                  \
                            struct test_ ## name, STRUCT, init, \
                            xfail)

#define DEFINE_UNION_TEST(name, init, xfail)                    \
                DEFINE_TEST(name ## _ ## init,                  \
                            union test_ ## name, STRUCT, init,  \
                            xfail)

#define DEFINE_STRUCT_TESTS(init, xfail)                        \
                DEFINE_STRUCT_TEST(small_hole, init, xfail);    \
                DEFINE_STRUCT_TEST(big_hole, init, xfail);      \
                DEFINE_STRUCT_TEST(trailing_hole, init, xfail); \
                DEFINE_STRUCT_TEST(packed, init, xfail)

#define DEFINE_STRUCT_INITIALIZER_TESTS(base, xfail)            \
                DEFINE_STRUCT_TESTS(base ## _ ## partial,       \
                                    xfail);                     \
                DEFINE_STRUCT_TESTS(base ## _ ## all, xfail)

#define DEFINE_UNION_INITIALIZER_TESTS(base, xfail)             \
                DEFINE_UNION_TESTS(base ## _ ## partial,        \
                                    xfail);                     \
                DEFINE_UNION_TESTS(base ## _ ## all, xfail)

#define DEFINE_UNION_TESTS(init, xfail)                         \
                DEFINE_UNION_TEST(same_sizes, init, xfail);     \
                DEFINE_UNION_TEST(small_start, init, xfail);    \
                DEFINE_UNION_TEST(small_end, init, xfail);

/* These should be fully initialized all the time! */
DEFINE_SCALAR_TESTS(zero, ALWAYS_PASS);
DEFINE_STRUCT_TESTS(zero, ALWAYS_PASS);
DEFINE_STRUCT_TESTS(old_zero, ALWAYS_PASS);
DEFINE_UNION_TESTS(zero, ALWAYS_PASS);
DEFINE_UNION_TESTS(old_zero, ALWAYS_PASS);
/* Struct initializers: padding may be left uninitialized. */
DEFINE_STRUCT_INITIALIZER_TESTS(static, STRONG_PASS);
DEFINE_STRUCT_INITIALIZER_TESTS(dynamic, STRONG_PASS);
DEFINE_STRUCT_INITIALIZER_TESTS(runtime, STRONG_PASS);
DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static, STRONG_PASS);
DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);
DEFINE_STRUCT_TESTS(assigned_copy, ALWAYS_FAIL);
DEFINE_UNION_INITIALIZER_TESTS(static, STRONG_PASS);
DEFINE_UNION_INITIALIZER_TESTS(dynamic, STRONG_PASS);
DEFINE_UNION_INITIALIZER_TESTS(runtime, STRONG_PASS);
DEFINE_UNION_INITIALIZER_TESTS(assigned_static, STRONG_PASS);
DEFINE_UNION_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);
DEFINE_UNION_TESTS(assigned_copy, ALWAYS_FAIL);
/* No initialization without compiler instrumentation. */
DEFINE_SCALAR_TESTS(none, STRONG_PASS);
DEFINE_STRUCT_TESTS(none, BYREF_PASS);
/* Initialization of members with __user attribute. */
DEFINE_TEST(user, struct test_user, STRUCT, none, USER_PASS);

/*
 * Check two uses through a variable declaration outside either path,
 * which was noticed as a special case in porting earlier stack init
 * compiler logic.
 */
static int noinline __leaf_switch_none(int path, bool fill)
{
        switch (path) {
                /*
                 * This is intentionally unreachable. To silence the
                 * warning, build with -Wno-switch-unreachable
                 */
                uint64_t var[10];

        case 1:
                target_start = &var;
                target_size = sizeof(var);
                if (fill) {
                        fill_start = &var;
                        fill_size = sizeof(var);

                        memset(fill_start, (forced_mask | 0x55) & FILL_BYTE, fill_size);
                }
                memcpy(check_buf, target_start, target_size);
                break;
        case 2:
                target_start = &var;
                target_size = sizeof(var);
                if (fill) {
                        fill_start = &var;
                        fill_size = sizeof(var);

                        memset(fill_start, (forced_mask | 0xaa) & FILL_BYTE, fill_size);
                }
                memcpy(check_buf, target_start, target_size);
                break;
        default:
                var[1] = 5;
                return var[1] & forced_mask;
        }
        return 0;
}

static noinline int leaf_switch_1_none(unsigned long sp, bool fill,
                                              uint64_t *arg)
{
        return __leaf_switch_none(1, fill);
}

static noinline int leaf_switch_2_none(unsigned long sp, bool fill,
                                              uint64_t *arg)
{
        return __leaf_switch_none(2, fill);
}

/*
 * These are expected to fail for most configurations because neither
 * GCC nor Clang have a way to perform initialization of variables in
 * non-code areas (i.e. in a switch statement before the first "case").
 * https://llvm.org/pr44916
 */
DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, ALWAYS_FAIL);
DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, ALWAYS_FAIL);

#define KUNIT_test_scalars(init)                        \
                KUNIT_CASE(test_u8_ ## init),           \
                KUNIT_CASE(test_u16_ ## init),          \
                KUNIT_CASE(test_u32_ ## init),          \
                KUNIT_CASE(test_u64_ ## init),          \
                KUNIT_CASE(test_char_array_ ## init)

#define KUNIT_test_structs(init)                        \
                KUNIT_CASE(test_small_hole_ ## init),   \
                KUNIT_CASE(test_big_hole_ ## init),     \
                KUNIT_CASE(test_trailing_hole_ ## init),\
                KUNIT_CASE(test_packed_ ## init)        \

#define KUNIT_test_unions(init)                         \
                KUNIT_CASE(test_same_sizes_ ## init),   \
                KUNIT_CASE(test_small_start_ ## init),  \
                KUNIT_CASE(test_small_end_ ## init)     \

static struct kunit_case stackinit_test_cases[] = {
        /* These are explicitly initialized and should always pass. */
        KUNIT_test_scalars(zero),
        KUNIT_test_structs(zero),
        KUNIT_test_structs(old_zero),
        KUNIT_test_unions(zero),
        KUNIT_test_unions(old_zero),
        /* Padding here appears to be accidentally always initialized? */
        KUNIT_test_structs(dynamic_partial),
        KUNIT_test_structs(assigned_dynamic_partial),
        KUNIT_test_unions(dynamic_partial),
        KUNIT_test_unions(assigned_dynamic_partial),
        /* Padding initialization depends on compiler behaviors. */
        KUNIT_test_structs(static_partial),
        KUNIT_test_structs(static_all),
        KUNIT_test_structs(dynamic_all),
        KUNIT_test_structs(runtime_partial),
        KUNIT_test_structs(runtime_all),
        KUNIT_test_structs(assigned_static_partial),
        KUNIT_test_structs(assigned_static_all),
        KUNIT_test_structs(assigned_dynamic_all),
        KUNIT_test_unions(static_partial),
        KUNIT_test_unions(static_all),
        KUNIT_test_unions(dynamic_all),
        KUNIT_test_unions(runtime_partial),
        KUNIT_test_unions(runtime_all),
        KUNIT_test_unions(assigned_static_partial),
        KUNIT_test_unions(assigned_static_all),
        KUNIT_test_unions(assigned_dynamic_all),
        /* Everything fails this since it effectively performs a memcpy(). */
        KUNIT_test_structs(assigned_copy),
        KUNIT_test_unions(assigned_copy),
        /* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
        KUNIT_test_scalars(none),
        KUNIT_CASE(test_switch_1_none),
        KUNIT_CASE(test_switch_2_none),
        /* STRUCTLEAK_BYREF should cover from here down. */
        KUNIT_test_structs(none),
        /* STRUCTLEAK will only cover this. */
        KUNIT_CASE(test_user),
        {}
};

static struct kunit_suite stackinit_test_suite = {
        .name = "stackinit",
        .test_cases = stackinit_test_cases,
};

kunit_test_suites(&stackinit_test_suite);

MODULE_DESCRIPTION("Test cases for compiler-based stack variable zeroing");
MODULE_LICENSE("GPL");