lib/ubsan.c

   1 /*
   2  * UBSAN error reporting functions
   3  *
   4  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
   5  * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  */
  12
  13 #include <linux/bitops.h>
  14 #include <linux/bug.h>
  15 #include <linux/ctype.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/types.h>
  19 #include <linux/sched.h>
  20
  21 #include "ubsan.h"
  22
  23 const char *type_check_kinds[] = {
  24         "load of",
  25         "store to",
  26         "reference binding to",
  27         "member access within",
  28         "member call on",
  29         "constructor call on",
  30         "downcast of",
  31         "downcast of"
  32 };
  33
  34 #define REPORTED_BIT 31
  35
  36 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
  37 #define COLUMN_MASK (~(1U << REPORTED_BIT))
  38 #define LINE_MASK   (~0U)
  39 #else
  40 #define COLUMN_MASK   (~0U)
  41 #define LINE_MASK (~(1U << REPORTED_BIT))
  42 #endif
  43
  44 #define VALUE_LENGTH 40
  45
  46 static bool was_reported(struct source_location *location)
  47 {
  48         return test_and_set_bit(REPORTED_BIT, &location->reported);
  49 }
  50
  51 static void print_source_location(const char *prefix,
  52                                 struct source_location *loc)
  53 {
  54         pr_err("%s %s:%d:%d\n", prefix, loc->file_name,
  55                 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
  56 }
  57
  58 static bool suppress_report(struct source_location *loc)
  59 {
  60         return current->in_ubsan || was_reported(loc);
  61 }
  62
  63 static bool type_is_int(struct type_descriptor *type)
  64 {
  65         return type->type_kind == type_kind_int;
  66 }
  67
  68 static bool type_is_signed(struct type_descriptor *type)
  69 {
  70         WARN_ON(!type_is_int(type));
  71         return  type->type_info & 1;
  72 }
  73
  74 static unsigned type_bit_width(struct type_descriptor *type)
  75 {
  76         return 1 << (type->type_info >> 1);
  77 }
  78
  79 static bool is_inline_int(struct type_descriptor *type)
  80 {
  81         unsigned inline_bits = sizeof(unsigned long)*8;
  82         unsigned bits = type_bit_width(type);
  83
  84         WARN_ON(!type_is_int(type));
  85
  86         return bits <= inline_bits;
  87 }
  88
  89 static s_max get_signed_val(struct type_descriptor *type, void *val)
  90 {
  91         if (is_inline_int(type)) {
  92                 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
  93                 unsigned long ulong_val = (unsigned long)val;
  94
  95                 return ((s_max)ulong_val) << extra_bits >> extra_bits;
  96         }
  97
  98         if (type_bit_width(type) == 64)
  99                 return *(s64 *)val;
 100
 101         return *(s_max *)val;
 102 }
 103
 104 static bool val_is_negative(struct type_descriptor *type, void *val)
 105 {
 106         return type_is_signed(type) && get_signed_val(type, val) < 0;
 107 }
 108
 109 static u_max get_unsigned_val(struct type_descriptor *type, void *val)
 110 {
 111         if (is_inline_int(type))
 112                 return (unsigned long)val;
 113
 114         if (type_bit_width(type) == 64)
 115                 return *(u64 *)val;
 116
 117         return *(u_max *)val;
 118 }
 119
 120 static void val_to_string(char *str, size_t size, struct type_descriptor *type,
 121                         void *value)
 122 {
 123         if (type_is_int(type)) {
 124                 if (type_bit_width(type) == 128) {
 125 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
 126                         u_max val = get_unsigned_val(type, value);
 127
 128                         scnprintf(str, size, "0x%08x%08x%08x%08x",
 129                                 (u32)(val >> 96),
 130                                 (u32)(val >> 64),
 131                                 (u32)(val >> 32),
 132                                 (u32)(val));
 133 #else
 134                         WARN_ON(1);
 135 #endif
 136                 } else if (type_is_signed(type)) {
 137                         scnprintf(str, size, "%lld",
 138                                 (s64)get_signed_val(type, value));
 139                 } else {
 140                         scnprintf(str, size, "%llu",
 141                                 (u64)get_unsigned_val(type, value));
 142                 }
 143         }
 144 }
 145
 146 static DEFINE_SPINLOCK(report_lock);
 147
 148 static void ubsan_prologue(struct source_location *location,
 149                         unsigned long *flags)
 150 {
 151         current->in_ubsan++;
 152         spin_lock_irqsave(&report_lock, *flags);
 153
 154         pr_err("========================================"
 155                 "========================================\n");
 156         print_source_location("UBSAN: Undefined behaviour in", location);
 157 }
 158
 159 static void ubsan_epilogue(unsigned long *flags)
 160 {
 161         dump_stack();
 162         pr_err("========================================"
 163                 "========================================\n");
 164         spin_unlock_irqrestore(&report_lock, *flags);
 165         current->in_ubsan--;
 166 }
 167
 168 static void handle_overflow(struct overflow_data *data, void *lhs,
 169                         void *rhs, char op)
 170 {
 171
 172         struct type_descriptor *type = data->type;
 173         unsigned long flags;
 174         char lhs_val_str[VALUE_LENGTH];
 175         char rhs_val_str[VALUE_LENGTH];
 176
 177         if (suppress_report(&data->location))
 178                 return;
 179
 180         ubsan_prologue(&data->location, &flags);
 181
 182         val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
 183         val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
 184         pr_err("%s integer overflow:\n",
 185                 type_is_signed(type) ? "signed" : "unsigned");
 186         pr_err("%s %c %s cannot be represented in type %s\n",
 187                 lhs_val_str,
 188                 op,
 189                 rhs_val_str,
 190                 type->type_name);
 191
 192         ubsan_epilogue(&flags);
 193 }
 194
 195 void __ubsan_handle_add_overflow(struct overflow_data *data,
 196                                 void *lhs, void *rhs)
 197 {
 198
 199         handle_overflow(data, lhs, rhs, '+');
 200 }
 201 EXPORT_SYMBOL(__ubsan_handle_add_overflow);
 202
 203 void __ubsan_handle_sub_overflow(struct overflow_data *data,
 204                                 void *lhs, void *rhs)
 205 {
 206         handle_overflow(data, lhs, rhs, '-');
 207 }
 208 EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
 209
 210 void __ubsan_handle_mul_overflow(struct overflow_data *data,
 211                                 void *lhs, void *rhs)
 212 {
 213         handle_overflow(data, lhs, rhs, '*');
 214 }
 215 EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
 216
 217 void __ubsan_handle_negate_overflow(struct overflow_data *data,
 218                                 void *old_val)
 219 {
 220         unsigned long flags;
 221         char old_val_str[VALUE_LENGTH];
 222
 223         if (suppress_report(&data->location))
 224                 return;
 225
 226         ubsan_prologue(&data->location, &flags);
 227
 228         val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
 229
 230         pr_err("negation of %s cannot be represented in type %s:\n",
 231                 old_val_str, data->type->type_name);
 232
 233         ubsan_epilogue(&flags);
 234 }
 235 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
 236
 237
 238 void __ubsan_handle_divrem_overflow(struct overflow_data *data,
 239                                 void *lhs, void *rhs)
 240 {
 241         unsigned long flags;
 242         char rhs_val_str[VALUE_LENGTH];
 243
 244         if (suppress_report(&data->location))
 245                 return;
 246
 247         ubsan_prologue(&data->location, &flags);
 248
 249         val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
 250
 251         if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
 252                 pr_err("division of %s by -1 cannot be represented in type %s\n",
 253                         rhs_val_str, data->type->type_name);
 254         else
 255                 pr_err("division by zero\n");
 256
 257         ubsan_epilogue(&flags);
 258 }
 259 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
 260
 261 static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
 262 {
 263         unsigned long flags;
 264
 265         if (suppress_report(data->location))
 266                 return;
 267
 268         ubsan_prologue(data->location, &flags);
 269
 270         pr_err("%s null pointer of type %s\n",
 271                 type_check_kinds[data->type_check_kind],
 272                 data->type->type_name);
 273
 274         ubsan_epilogue(&flags);
 275 }
 276
 277 static void handle_misaligned_access(struct type_mismatch_data_common *data,
 278                                 unsigned long ptr)
 279 {
 280         unsigned long flags;
 281
 282         if (suppress_report(data->location))
 283                 return;
 284
 285         ubsan_prologue(data->location, &flags);
 286
 287         pr_err("%s misaligned address %p for type %s\n",
 288                 type_check_kinds[data->type_check_kind],
 289                 (void *)ptr, data->type->type_name);
 290         pr_err("which requires %ld byte alignment\n", data->alignment);
 291
 292         ubsan_epilogue(&flags);
 293 }
 294
 295 static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
 296                                         unsigned long ptr)
 297 {
 298         unsigned long flags;
 299
 300         if (suppress_report(data->location))
 301                 return;
 302
 303         ubsan_prologue(data->location, &flags);
 304         pr_err("%s address %p with insufficient space\n",
 305                 type_check_kinds[data->type_check_kind],
 306                 (void *) ptr);
 307         pr_err("for an object of type %s\n", data->type->type_name);
 308         ubsan_epilogue(&flags);
 309 }
 310
 311 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
 312                                 unsigned long ptr)
 313 {
 314
 315         if (!ptr)
 316                 handle_null_ptr_deref(data);
 317         else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
 318                 handle_misaligned_access(data, ptr);
 319         else
 320                 handle_object_size_mismatch(data, ptr);
 321 }
 322
 323 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
 324                                 void *ptr)
 325 {
 326         struct type_mismatch_data_common common_data = {
 327                 .location = &data->location,
 328                 .type = data->type,
 329                 .alignment = data->alignment,
 330                 .type_check_kind = data->type_check_kind
 331         };
 332
 333         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
 334 }
 335 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
 336
 337 void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
 338                                 void *ptr)
 339 {
 340
 341         struct type_mismatch_data_common common_data = {
 342                 .location = &data->location,
 343                 .type = data->type,
 344                 .alignment = 1UL << data->log_alignment,
 345                 .type_check_kind = data->type_check_kind
 346         };
 347
 348         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
 349 }
 350 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
 351
 352 void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data,
 353                                         void *bound)
 354 {
 355         unsigned long flags;
 356         char bound_str[VALUE_LENGTH];
 357
 358         if (suppress_report(&data->location))
 359                 return;
 360
 361         ubsan_prologue(&data->location, &flags);
 362
 363         val_to_string(bound_str, sizeof(bound_str), data->type, bound);
 364         pr_err("variable length array bound value %s <= 0\n", bound_str);
 365
 366         ubsan_epilogue(&flags);
 367 }
 368 EXPORT_SYMBOL(__ubsan_handle_vla_bound_not_positive);
 369
 370 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index)
 371 {
 372         unsigned long flags;
 373         char index_str[VALUE_LENGTH];
 374
 375         if (suppress_report(&data->location))
 376                 return;
 377
 378         ubsan_prologue(&data->location, &flags);
 379
 380         val_to_string(index_str, sizeof(index_str), data->index_type, index);
 381         pr_err("index %s is out of range for type %s\n", index_str,
 382                 data->array_type->type_name);
 383         ubsan_epilogue(&flags);
 384 }
 385 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
 386
 387 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
 388                                         void *lhs, void *rhs)
 389 {
 390         unsigned long flags;
 391         struct type_descriptor *rhs_type = data->rhs_type;
 392         struct type_descriptor *lhs_type = data->lhs_type;
 393         char rhs_str[VALUE_LENGTH];
 394         char lhs_str[VALUE_LENGTH];
 395
 396         if (suppress_report(&data->location))
 397                 return;
 398
 399         ubsan_prologue(&data->location, &flags);
 400
 401         val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
 402         val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
 403
 404         if (val_is_negative(rhs_type, rhs))
 405                 pr_err("shift exponent %s is negative\n", rhs_str);
 406
 407         else if (get_unsigned_val(rhs_type, rhs) >=
 408                 type_bit_width(lhs_type))
 409                 pr_err("shift exponent %s is too large for %u-bit type %s\n",
 410                         rhs_str,
 411                         type_bit_width(lhs_type),
 412                         lhs_type->type_name);
 413         else if (val_is_negative(lhs_type, lhs))
 414                 pr_err("left shift of negative value %s\n",
 415                         lhs_str);
 416         else
 417                 pr_err("left shift of %s by %s places cannot be"
 418                         " represented in type %s\n",
 419                         lhs_str, rhs_str,
 420                         lhs_type->type_name);
 421
 422         ubsan_epilogue(&flags);
 423 }
 424 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
 425
 426
 427 void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
 428 {
 429         unsigned long flags;
 430
 431         ubsan_prologue(&data->location, &flags);
 432         pr_err("calling __builtin_unreachable()\n");
 433         ubsan_epilogue(&flags);
 434         panic("can't return from __builtin_unreachable()");
 435 }
 436 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
 437
 438 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
 439                                 void *val)
 440 {
 441         unsigned long flags;
 442         char val_str[VALUE_LENGTH];
 443
 444         if (suppress_report(&data->location))
 445                 return;
 446
 447         ubsan_prologue(&data->location, &flags);
 448
 449         val_to_string(val_str, sizeof(val_str), data->type, val);
 450
 451         pr_err("load of value %s is not a valid value for type %s\n",
 452                 val_str, data->type->type_name);
 453
 454         ubsan_epilogue(&flags);
 455 }
 456 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);