cregit-Linux how code gets into the kernel

Release 4.9 lib/ubsan.c

Directory: lib
/*
 * UBSAN error reporting functions
 *
 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#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 "ubsan.h"


const char *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); }

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static void print_source_location(const char *prefix, struct source_location *loc) { pr_err("%s %s:%d:%d\n", prefix, loc->file_name, loc->line & LINE_MASK, loc->column & COLUMN_MASK); }

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

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

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

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

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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; }

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static s_max get_signed_val(struct type_descriptor *type, unsigned long val) { if (is_inline_int(type)) { unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type); return ((s_max)val) << extra_bits >> extra_bits; } if (type_bit_width(type) == 64) return *(s64 *)val; return *(s_max *)val; }

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

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static u_max get_unsigned_val(struct type_descriptor *type, unsigned long val) { if (is_inline_int(type)) return val; if (type_bit_width(type) == 64) return *(u64 *)val; return *(u_max *)val; }

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static void val_to_string(char *str, size_t size, struct type_descriptor *type, unsigned long value) { if (type_is_int(type)) { if (type_bit_width(type) == 128) { #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_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)); } } }

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static bool location_is_valid(struct source_location *loc) { return loc->file_name != NULL; }

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static DEFINE_SPINLOCK(report_lock);
static void ubsan_prologue(struct source_location *location, unsigned long *flags) { current->in_ubsan++; spin_lock_irqsave(&report_lock, *flags); pr_err("========================================" "========================================\n"); print_source_location("UBSAN: Undefined behaviour in", location); }

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static void ubsan_epilogue(unsigned long *flags) { dump_stack(); pr_err("========================================" "========================================\n"); spin_unlock_irqrestore(&report_lock, *flags); current->in_ubsan--; }

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static void handle_overflow(struct overflow_data *data, unsigned long lhs, unsigned long rhs, char op) { struct type_descriptor *type = data->type; unsigned long flags; char lhs_val_str[VALUE_LENGTH]; char rhs_val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); 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 integer overflow:\n", type_is_signed(type) ? "signed" : "unsigned"); pr_err("%s %c %s cannot be represented in type %s\n", lhs_val_str, op, rhs_val_str, type->type_name); ubsan_epilogue(&flags); }

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void __ubsan_handle_add_overflow(struct overflow_data *data, unsigned long lhs, unsigned long rhs) { handle_overflow(data, lhs, rhs, '+'); }

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EXPORT_SYMBOL(__ubsan_handle_add_overflow);
void __ubsan_handle_sub_overflow(struct overflow_data *data, unsigned long lhs, unsigned long rhs) { handle_overflow(data, lhs, rhs, '-'); }

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EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
void __ubsan_handle_mul_overflow(struct overflow_data *data, unsigned long lhs, unsigned long rhs) { handle_overflow(data, lhs, rhs, '*'); }

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EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
void __ubsan_handle_negate_overflow(struct overflow_data *data, unsigned long old_val) { unsigned long flags; char old_val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); 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(&flags); }

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EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
void __ubsan_handle_divrem_overflow(struct overflow_data *data, unsigned long lhs, unsigned long rhs) { unsigned long flags; char rhs_val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 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", rhs_val_str, data->type->type_name); else pr_err("division by zero\n"); ubsan_epilogue(&flags); }

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EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
static void handle_null_ptr_deref(struct type_mismatch_data *data) { unsigned long flags; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); pr_err("%s null pointer of type %s\n", type_check_kinds[data->type_check_kind], data->type->type_name); ubsan_epilogue(&flags); }

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static void handle_missaligned_access(struct type_mismatch_data *data, unsigned long ptr) { unsigned long flags; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); 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(&flags); }

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static void handle_object_size_mismatch(struct type_mismatch_data *data, unsigned long ptr) { unsigned long flags; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); 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(&flags); }

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void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, unsigned long ptr) { if (!ptr) handle_null_ptr_deref(data); else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) handle_missaligned_access(data, ptr); else handle_object_size_mismatch(data, ptr); }

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EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
void __ubsan_handle_nonnull_return(struct nonnull_return_data *data) { unsigned long flags; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); pr_err("null pointer returned from function declared to never return null\n"); if (location_is_valid(&data->attr_location)) print_source_location("returns_nonnull attribute specified in", &data->attr_location); ubsan_epilogue(&flags); }

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EXPORT_SYMBOL(__ubsan_handle_nonnull_return);
void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data, unsigned long bound) { unsigned long flags; char bound_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); val_to_string(bound_str, sizeof(bound_str), data->type, bound); pr_err("variable length array bound value %s <= 0\n", bound_str); ubsan_epilogue(&flags); }

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EXPORT_SYMBOL(__ubsan_handle_vla_bound_not_positive);
void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, unsigned long index) { unsigned long flags; char index_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); 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(&flags); }

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EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, unsigned long lhs, unsigned long rhs) { unsigned long flags; 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]; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); 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(&flags); }

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EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
void __noreturn __ubsan_handle_builtin_unreachable(struct unreachable_data *data) { unsigned long flags; ubsan_prologue(&data->location, &flags); pr_err("calling __builtin_unreachable()\n"); ubsan_epilogue(&flags); panic("can't return from __builtin_unreachable()"); }

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EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
void __ubsan_handle_load_invalid_value(struct invalid_value_data *data, unsigned long val) { unsigned long flags; char val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; ubsan_prologue(&data->location, &flags); 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(&flags); }

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EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);

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Directory: lib