// SPDX-License-Identifier: GPL-2.0-only
/*
 * UBSAN error reporting functions
 *
 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
 */

#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/ubsan.h>
#include <kunit/test-bug.h>

#include "ubsan.h"

#if defined(CONFIG_UBSAN_TRAP) || defined(CONFIG_UBSAN_KVM_EL2)
/*
 * Only include matches for UBSAN checks that are actually compiled in.
 * The mappings of struct SanitizerKind (the -fsanitize=xxx args) to
 * enum SanitizerHandler (the traps) in Clang is in clang/lib/CodeGen/.
 */
const char *report_ubsan_failure(u32 check_type)
{
        switch (check_type) {
#ifdef CONFIG_UBSAN_BOUNDS
        /*
         * SanitizerKind::ArrayBounds and SanitizerKind::LocalBounds
         * emit SanitizerHandler::OutOfBounds.
         */
        case ubsan_out_of_bounds:
                return "UBSAN: array index out of bounds";
#endif
#ifdef CONFIG_UBSAN_SHIFT
        /*
         * SanitizerKind::ShiftBase and SanitizerKind::ShiftExponent
         * emit SanitizerHandler::ShiftOutOfBounds.
         */
        case ubsan_shift_out_of_bounds:
                return "UBSAN: shift out of bounds";
#endif
#if defined(CONFIG_UBSAN_DIV_ZERO) || defined(CONFIG_UBSAN_INTEGER_WRAP)
        /*
         * SanitizerKind::IntegerDivideByZero and
         * SanitizerKind::SignedIntegerOverflow emit
         * SanitizerHandler::DivremOverflow.
         */
        case ubsan_divrem_overflow:
                return "UBSAN: divide/remainder overflow";
#endif
#ifdef CONFIG_UBSAN_UNREACHABLE
        /*
         * SanitizerKind::Unreachable emits
         * SanitizerHandler::BuiltinUnreachable.
         */
        case ubsan_builtin_unreachable:
                return "UBSAN: unreachable code";
#endif
#if defined(CONFIG_UBSAN_BOOL) || defined(CONFIG_UBSAN_ENUM)
        /*
         * SanitizerKind::Bool and SanitizerKind::Enum emit
         * SanitizerHandler::LoadInvalidValue.
         */
        case ubsan_load_invalid_value:
                return "UBSAN: loading invalid value";
#endif
#ifdef CONFIG_UBSAN_ALIGNMENT
        /*
         * SanitizerKind::Alignment emits SanitizerHandler::TypeMismatch
         * or SanitizerHandler::AlignmentAssumption.
         */
        case ubsan_alignment_assumption:
                return "UBSAN: alignment assumption";
        case ubsan_type_mismatch:
                return "UBSAN: type mismatch";
#endif
#ifdef CONFIG_UBSAN_INTEGER_WRAP
        /*
         * SanitizerKind::SignedIntegerOverflow emits
         * SanitizerHandler::AddOverflow, SanitizerHandler::SubOverflow,
         * or SanitizerHandler::MulOverflow.
         */
        case ubsan_add_overflow:
                return "UBSAN: integer addition overflow";
        case ubsan_sub_overflow:
                return "UBSAN: integer subtraction overflow";
        case ubsan_mul_overflow:
                return "UBSAN: integer multiplication overflow";
#endif
        default:
                return "UBSAN: unrecognized failure code";
        }
}

#endif

#ifndef CONFIG_UBSAN_TRAP
static const char * const type_check_kinds[] = {
        "load of",
        "store to",
        "reference binding to",
        "member access within",
        "member call on",
        "constructor call on",
        "downcast of",
        "downcast of"
};

#define REPORTED_BIT 31

#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
#define COLUMN_MASK (~(1U << REPORTED_BIT))
#define LINE_MASK   (~0U)
#else
#define COLUMN_MASK   (~0U)
#define LINE_MASK (~(1U << REPORTED_BIT))
#endif

#define VALUE_LENGTH 40

static bool was_reported(struct source_location *location)
{
        return test_and_set_bit(REPORTED_BIT, &location->reported);
}

static bool suppress_report(struct source_location *loc)
{
        return current->in_ubsan || was_reported(loc);
}

static bool type_is_int(struct type_descriptor *type)
{
        return type->type_kind == type_kind_int;
}

static bool type_is_signed(struct type_descriptor *type)
{
        WARN_ON(!type_is_int(type));
        return  type->type_info & 1;
}

static unsigned type_bit_width(struct type_descriptor *type)
{
        return 1 << (type->type_info >> 1);
}

static bool is_inline_int(struct type_descriptor *type)
{
        unsigned inline_bits = sizeof(unsigned long)*8;
        unsigned bits = type_bit_width(type);

        WARN_ON(!type_is_int(type));

        return bits <= inline_bits;
}

static s_max get_signed_val(struct type_descriptor *type, void *val)
{
        if (is_inline_int(type)) {
                unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
                unsigned long ulong_val = (unsigned long)val;

                return ((s_max)ulong_val) << extra_bits >> extra_bits;
        }

        if (type_bit_width(type) == 64)
                return *(s64 *)val;

        return *(s_max *)val;
}

static bool val_is_negative(struct type_descriptor *type, void *val)
{
        return type_is_signed(type) && get_signed_val(type, val) < 0;
}

static u_max get_unsigned_val(struct type_descriptor *type, void *val)
{
        if (is_inline_int(type))
                return (unsigned long)val;

        if (type_bit_width(type) == 64)
                return *(u64 *)val;

        return *(u_max *)val;
}

static void val_to_string(char *str, size_t size, struct type_descriptor *type,
                        void *value)
{
        if (type_is_int(type)) {
                if (type_bit_width(type) == 128) {
#if defined(CONFIG_ARCH_SUPPORTS_INT128)
                        u_max val = get_unsigned_val(type, value);

                        scnprintf(str, size, "0x%08x%08x%08x%08x",
                                (u32)(val >> 96),
                                (u32)(val >> 64),
                                (u32)(val >> 32),
                                (u32)(val));
#else
                        WARN_ON(1);
#endif
                } else if (type_is_signed(type)) {
                        scnprintf(str, size, "%lld",
                                (s64)get_signed_val(type, value));
                } else {
                        scnprintf(str, size, "%llu",
                                (u64)get_unsigned_val(type, value));
                }
        }
}

static void ubsan_prologue(struct source_location *loc, const char *reason)
{
        current->in_ubsan++;

        pr_warn(CUT_HERE);

        pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
                loc->line & LINE_MASK, loc->column & COLUMN_MASK);

        kunit_fail_current_test("%s in %s", reason, loc->file_name);
}

static void ubsan_epilogue(void)
{
        dump_stack();
        pr_warn("---[ end trace ]---\n");

        current->in_ubsan--;

        check_panic_on_warn("UBSAN");
}

static void handle_overflow(struct overflow_data *data, void *lhs,
                        void *rhs, char op)
{

        struct type_descriptor *type = data->type;
        char lhs_val_str[VALUE_LENGTH];
        char rhs_val_str[VALUE_LENGTH];

        if (suppress_report(&data->location))
                return;

        ubsan_prologue(&data->location, type_is_signed(type) ?
                        "signed-integer-overflow" :
                        "unsigned-integer-overflow");

        val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
        val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
        pr_err("%s %c %s cannot be represented in type %s\n",
                lhs_val_str,
                op,
                rhs_val_str,
                type->type_name);

        ubsan_epilogue();
}

void __ubsan_handle_add_overflow(void *data,
                                void *lhs, void *rhs)
{

        handle_overflow(data, lhs, rhs, '+');
}
EXPORT_SYMBOL(__ubsan_handle_add_overflow);

void __ubsan_handle_sub_overflow(void *data,
                                void *lhs, void *rhs)
{
        handle_overflow(data, lhs, rhs, '-');
}
EXPORT_SYMBOL(__ubsan_handle_sub_overflow);

void __ubsan_handle_mul_overflow(void *data,
                                void *lhs, void *rhs)
{
        handle_overflow(data, lhs, rhs, '*');
}
EXPORT_SYMBOL(__ubsan_handle_mul_overflow);

void __ubsan_handle_negate_overflow(void *_data, void *old_val)
{
        struct overflow_data *data = _data;
        char old_val_str[VALUE_LENGTH];

        if (suppress_report(&data->location))
                return;

        ubsan_prologue(&data->location, "negation-overflow");

        val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);

        pr_err("negation of %s cannot be represented in type %s:\n",
                old_val_str, data->type->type_name);

        ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_negate_overflow);

void __ubsan_handle_implicit_conversion(void *_data, void *from_val, void *to_val)
{
        struct implicit_conversion_data *data = _data;
        char from_val_str[VALUE_LENGTH];
        char to_val_str[VALUE_LENGTH];

        if (suppress_report(&data->location))
                return;

        val_to_string(from_val_str, sizeof(from_val_str), data->from_type, from_val);
        val_to_string(to_val_str, sizeof(to_val_str), data->to_type, to_val);

        ubsan_prologue(&data->location, "implicit-conversion");

        pr_err("cannot represent %s value %s during %s %s, truncated to %s\n",
                data->from_type->type_name,
                from_val_str,
                type_check_kinds[data->type_check_kind],
                data->to_type->type_name,
                to_val_str);

        ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_implicit_conversion);

void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
{
        struct overflow_data *data = _data;
        char lhs_val_str[VALUE_LENGTH];

        if (suppress_report(&data->location))
                return;

        ubsan_prologue(&data->location, "division-overflow");

        val_to_string(lhs_val_str, sizeof(lhs_val_str), data->type, lhs);

        if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
                pr_err("division of %s by -1 cannot be represented in type %s\n",
                        lhs_val_str, data->type->type_name);
        else
                pr_err("division by zero\n");

        ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);

static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
{
        if (suppress_report(data->location))
                return;

        ubsan_prologue(data->location, "null-ptr-deref");

        pr_err("%s null pointer of type %s\n",
                type_check_kinds[data->type_check_kind],
                data->type->type_name);

        ubsan_epilogue();
}

static void handle_misaligned_access(struct type_mismatch_data_common *data,
                                unsigned long ptr)
{
        if (suppress_report(data->location))
                return;

        ubsan_prologue(data->location, "misaligned-access");

        pr_err("%s misaligned address %p for type %s\n",
                type_check_kinds[data->type_check_kind],
                (void *)ptr, data->type->type_name);
        pr_err("which requires %ld byte alignment\n", data->alignment);

        ubsan_epilogue();
}

static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
                                        unsigned long ptr)
{
        if (suppress_report(data->location))
                return;

        ubsan_prologue(data->location, "object-size-mismatch");
        pr_err("%s address %p with insufficient space\n",
                type_check_kinds[data->type_check_kind],
                (void *) ptr);
        pr_err("for an object of type %s\n", data->type->type_name);
        ubsan_epilogue();
}

static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
                                unsigned long ptr)
{
        unsigned long flags = user_access_save();

        if (!ptr)
                handle_null_ptr_deref(data);
        else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
                handle_misaligned_access(data, ptr);
        else
                handle_object_size_mismatch(data, ptr);

        user_access_restore(flags);
}

void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
                                void *ptr)
{
        struct type_mismatch_data_common common_data = {
                .location = &data->location,
                .type = data->type,
                .alignment = data->alignment,
                .type_check_kind = data->type_check_kind
        };

        ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
}
EXPORT_SYMBOL(__ubsan_handle_type_mismatch);

void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
{
        struct type_mismatch_data_v1 *data = _data;
        struct type_mismatch_data_common common_data = {
                .location = &data->location,
                .type = data->type,
                .alignment = 1UL << data->log_alignment,
                .type_check_kind = data->type_check_kind
        };

        ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
}
EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);

void __ubsan_handle_out_of_bounds(void *_data, void *index)
{
        struct out_of_bounds_data *data = _data;
        char index_str[VALUE_LENGTH];

        if (suppress_report(&data->location))
                return;

        ubsan_prologue(&data->location, "array-index-out-of-bounds");

        val_to_string(index_str, sizeof(index_str), data->index_type, index);
        pr_err("index %s is out of range for type %s\n", index_str,
                data->array_type->type_name);
        ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);

void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
{
        struct shift_out_of_bounds_data *data = _data;
        struct type_descriptor *rhs_type = data->rhs_type;
        struct type_descriptor *lhs_type = data->lhs_type;
        char rhs_str[VALUE_LENGTH];
        char lhs_str[VALUE_LENGTH];
        unsigned long ua_flags = user_access_save();

        if (suppress_report(&data->location))
                goto out;

        ubsan_prologue(&data->location, "shift-out-of-bounds");

        val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
        val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);

        if (val_is_negative(rhs_type, rhs))
                pr_err("shift exponent %s is negative\n", rhs_str);

        else if (get_unsigned_val(rhs_type, rhs) >=
                type_bit_width(lhs_type))
                pr_err("shift exponent %s is too large for %u-bit type %s\n",
                        rhs_str,
                        type_bit_width(lhs_type),
                        lhs_type->type_name);
        else if (val_is_negative(lhs_type, lhs))
                pr_err("left shift of negative value %s\n",
                        lhs_str);
        else
                pr_err("left shift of %s by %s places cannot be"
                        " represented in type %s\n",
                        lhs_str, rhs_str,
                        lhs_type->type_name);

        ubsan_epilogue();
out:
        user_access_restore(ua_flags);
}
EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);


void __ubsan_handle_builtin_unreachable(void *_data)
{
        struct unreachable_data *data = _data;
        ubsan_prologue(&data->location, "unreachable");
        pr_err("calling __builtin_unreachable()\n");
        ubsan_epilogue();
        panic("can't return from __builtin_unreachable()");
}
EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);

void __ubsan_handle_load_invalid_value(void *_data, void *val)
{
        struct invalid_value_data *data = _data;
        char val_str[VALUE_LENGTH];
        unsigned long ua_flags = user_access_save();

        if (suppress_report(&data->location))
                goto out;

        ubsan_prologue(&data->location, "invalid-load");

        val_to_string(val_str, sizeof(val_str), data->type, val);

        pr_err("load of value %s is not a valid value for type %s\n",
                val_str, data->type->type_name);

        ubsan_epilogue();
out:
        user_access_restore(ua_flags);
}
EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);

void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
                                         unsigned long align,
                                         unsigned long offset)
{
        struct alignment_assumption_data *data = _data;
        unsigned long real_ptr;

        if (suppress_report(&data->location))
                return;

        ubsan_prologue(&data->location, "alignment-assumption");

        if (offset)
                pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
                       align, offset, data->type->type_name);
        else
                pr_err("assumption of %lu byte alignment for pointer of type %s failed",
                       align, data->type->type_name);

        real_ptr = ptr - offset;
        pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
               offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
               real_ptr & (align - 1));

        ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);

#endif /* !CONFIG_UBSAN_TRAP */