lib/ubsan.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * UBSAN error reporting functions
   4  *
   5  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
   6  * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
   7  */
   8
   9 #include <linux/bitops.h>
  10 #include <linux/bug.h>
  11 #include <linux/ctype.h>
  12 #include <linux/init.h>
  13 #include <linux/kernel.h>
  14 #include <linux/types.h>
  15 #include <linux/sched.h>
  16 #include <linux/uaccess.h>
  17 #include <linux/ubsan.h>
  18 #include <kunit/test-bug.h>
  19
  20 #include "ubsan.h"
  21
  22 #if defined(CONFIG_UBSAN_TRAP) || defined(CONFIG_UBSAN_KVM_EL2)
  23 /*
  24  * Only include matches for UBSAN checks that are actually compiled in.
  25  * The mappings of struct SanitizerKind (the -fsanitize=xxx args) to
  26  * enum SanitizerHandler (the traps) in Clang is in clang/lib/CodeGen/.
  27  */
  28 const char *report_ubsan_failure(u32 check_type)
  29 {
  30         switch (check_type) {
  31 #ifdef CONFIG_UBSAN_BOUNDS
  32         /*
  33          * SanitizerKind::ArrayBounds and SanitizerKind::LocalBounds
  34          * emit SanitizerHandler::OutOfBounds.
  35          */
  36         case ubsan_out_of_bounds:
  37                 return "UBSAN: array index out of bounds";
  38 #endif
  39 #ifdef CONFIG_UBSAN_SHIFT
  40         /*
  41          * SanitizerKind::ShiftBase and SanitizerKind::ShiftExponent
  42          * emit SanitizerHandler::ShiftOutOfBounds.
  43          */
  44         case ubsan_shift_out_of_bounds:
  45                 return "UBSAN: shift out of bounds";
  46 #endif
  47 #if defined(CONFIG_UBSAN_DIV_ZERO) || defined(CONFIG_UBSAN_INTEGER_WRAP)
  48         /*
  49          * SanitizerKind::IntegerDivideByZero and
  50          * SanitizerKind::SignedIntegerOverflow emit
  51          * SanitizerHandler::DivremOverflow.
  52          */
  53         case ubsan_divrem_overflow:
  54                 return "UBSAN: divide/remainder overflow";
  55 #endif
  56 #ifdef CONFIG_UBSAN_UNREACHABLE
  57         /*
  58          * SanitizerKind::Unreachable emits
  59          * SanitizerHandler::BuiltinUnreachable.
  60          */
  61         case ubsan_builtin_unreachable:
  62                 return "UBSAN: unreachable code";
  63 #endif
  64 #if defined(CONFIG_UBSAN_BOOL) || defined(CONFIG_UBSAN_ENUM)
  65         /*
  66          * SanitizerKind::Bool and SanitizerKind::Enum emit
  67          * SanitizerHandler::LoadInvalidValue.
  68          */
  69         case ubsan_load_invalid_value:
  70                 return "UBSAN: loading invalid value";
  71 #endif
  72 #ifdef CONFIG_UBSAN_ALIGNMENT
  73         /*
  74          * SanitizerKind::Alignment emits SanitizerHandler::TypeMismatch
  75          * or SanitizerHandler::AlignmentAssumption.
  76          */
  77         case ubsan_alignment_assumption:
  78                 return "UBSAN: alignment assumption";
  79         case ubsan_type_mismatch:
  80                 return "UBSAN: type mismatch";
  81 #endif
  82 #ifdef CONFIG_UBSAN_INTEGER_WRAP
  83         /*
  84          * SanitizerKind::SignedIntegerOverflow emits
  85          * SanitizerHandler::AddOverflow, SanitizerHandler::SubOverflow,
  86          * or SanitizerHandler::MulOverflow.
  87          */
  88         case ubsan_add_overflow:
  89                 return "UBSAN: integer addition overflow";
  90         case ubsan_sub_overflow:
  91                 return "UBSAN: integer subtraction overflow";
  92         case ubsan_mul_overflow:
  93                 return "UBSAN: integer multiplication overflow";
  94 #endif
  95         default:
  96                 return "UBSAN: unrecognized failure code";
  97         }
  98 }
  99
 100 #endif
 101
 102 #ifndef CONFIG_UBSAN_TRAP
 103 static const char * const type_check_kinds[] = {
 104         "load of",
 105         "store to",
 106         "reference binding to",
 107         "member access within",
 108         "member call on",
 109         "constructor call on",
 110         "downcast of",
 111         "downcast of"
 112 };
 113
 114 #define REPORTED_BIT 31
 115
 116 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
 117 #define COLUMN_MASK (~(1U << REPORTED_BIT))
 118 #define LINE_MASK   (~0U)
 119 #else
 120 #define COLUMN_MASK   (~0U)
 121 #define LINE_MASK (~(1U << REPORTED_BIT))
 122 #endif
 123
 124 #define VALUE_LENGTH 40
 125
 126 static bool was_reported(struct source_location *location)
 127 {
 128         return test_and_set_bit(REPORTED_BIT, &location->reported);
 129 }
 130
 131 static bool suppress_report(struct source_location *loc)
 132 {
 133         return current->in_ubsan || was_reported(loc);
 134 }
 135
 136 static bool type_is_int(struct type_descriptor *type)
 137 {
 138         return type->type_kind == type_kind_int;
 139 }
 140
 141 static bool type_is_signed(struct type_descriptor *type)
 142 {
 143         WARN_ON(!type_is_int(type));
 144         return  type->type_info & 1;
 145 }
 146
 147 static unsigned type_bit_width(struct type_descriptor *type)
 148 {
 149         return 1 << (type->type_info >> 1);
 150 }
 151
 152 static bool is_inline_int(struct type_descriptor *type)
 153 {
 154         unsigned inline_bits = sizeof(unsigned long)*8;
 155         unsigned bits = type_bit_width(type);
 156
 157         WARN_ON(!type_is_int(type));
 158
 159         return bits <= inline_bits;
 160 }
 161
 162 static s_max get_signed_val(struct type_descriptor *type, void *val)
 163 {
 164         if (is_inline_int(type)) {
 165                 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
 166                 unsigned long ulong_val = (unsigned long)val;
 167
 168                 return ((s_max)ulong_val) << extra_bits >> extra_bits;
 169         }
 170
 171         if (type_bit_width(type) == 64)
 172                 return *(s64 *)val;
 173
 174         return *(s_max *)val;
 175 }
 176
 177 static bool val_is_negative(struct type_descriptor *type, void *val)
 178 {
 179         return type_is_signed(type) && get_signed_val(type, val) < 0;
 180 }
 181
 182 static u_max get_unsigned_val(struct type_descriptor *type, void *val)
 183 {
 184         if (is_inline_int(type))
 185                 return (unsigned long)val;
 186
 187         if (type_bit_width(type) == 64)
 188                 return *(u64 *)val;
 189
 190         return *(u_max *)val;
 191 }
 192
 193 static void val_to_string(char *str, size_t size, struct type_descriptor *type,
 194                         void *value)
 195 {
 196         if (type_is_int(type)) {
 197                 if (type_bit_width(type) == 128) {
 198 #if defined(CONFIG_ARCH_SUPPORTS_INT128)
 199                         u_max val = get_unsigned_val(type, value);
 200
 201                         scnprintf(str, size, "0x%08x%08x%08x%08x",
 202                                 (u32)(val >> 96),
 203                                 (u32)(val >> 64),
 204                                 (u32)(val >> 32),
 205                                 (u32)(val));
 206 #else
 207                         WARN_ON(1);
 208 #endif
 209                 } else if (type_is_signed(type)) {
 210                         scnprintf(str, size, "%lld",
 211                                 (s64)get_signed_val(type, value));
 212                 } else {
 213                         scnprintf(str, size, "%llu",
 214                                 (u64)get_unsigned_val(type, value));
 215                 }
 216         }
 217 }
 218
 219 static void ubsan_prologue(struct source_location *loc, const char *reason)
 220 {
 221         current->in_ubsan++;
 222
 223         pr_warn(CUT_HERE);
 224
 225         pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
 226                 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
 227
 228         kunit_fail_current_test("%s in %s", reason, loc->file_name);
 229 }
 230
 231 static void ubsan_epilogue(void)
 232 {
 233         dump_stack();
 234         pr_warn("---[ end trace ]---\n");
 235
 236         current->in_ubsan--;
 237
 238         check_panic_on_warn("UBSAN");
 239 }
 240
 241 static void handle_overflow(struct overflow_data *data, void *lhs,
 242                         void *rhs, char op)
 243 {
 244
 245         struct type_descriptor *type = data->type;
 246         char lhs_val_str[VALUE_LENGTH];
 247         char rhs_val_str[VALUE_LENGTH];
 248
 249         if (suppress_report(&data->location))
 250                 return;
 251
 252         ubsan_prologue(&data->location, type_is_signed(type) ?
 253                         "signed-integer-overflow" :
 254                         "unsigned-integer-overflow");
 255
 256         val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
 257         val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
 258         pr_err("%s %c %s cannot be represented in type %s\n",
 259                 lhs_val_str,
 260                 op,
 261                 rhs_val_str,
 262                 type->type_name);
 263
 264         ubsan_epilogue();
 265 }
 266
 267 void __ubsan_handle_add_overflow(void *data,
 268                                 void *lhs, void *rhs)
 269 {
 270
 271         handle_overflow(data, lhs, rhs, '+');
 272 }
 273 EXPORT_SYMBOL(__ubsan_handle_add_overflow);
 274
 275 void __ubsan_handle_sub_overflow(void *data,
 276                                 void *lhs, void *rhs)
 277 {
 278         handle_overflow(data, lhs, rhs, '-');
 279 }
 280 EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
 281
 282 void __ubsan_handle_mul_overflow(void *data,
 283                                 void *lhs, void *rhs)
 284 {
 285         handle_overflow(data, lhs, rhs, '*');
 286 }
 287 EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
 288
 289 void __ubsan_handle_negate_overflow(void *_data, void *old_val)
 290 {
 291         struct overflow_data *data = _data;
 292         char old_val_str[VALUE_LENGTH];
 293
 294         if (suppress_report(&data->location))
 295                 return;
 296
 297         ubsan_prologue(&data->location, "negation-overflow");
 298
 299         val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
 300
 301         pr_err("negation of %s cannot be represented in type %s:\n",
 302                 old_val_str, data->type->type_name);
 303
 304         ubsan_epilogue();
 305 }
 306 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
 307
 308 void __ubsan_handle_implicit_conversion(void *_data, void *from_val, void *to_val)
 309 {
 310         struct implicit_conversion_data *data = _data;
 311         char from_val_str[VALUE_LENGTH];
 312         char to_val_str[VALUE_LENGTH];
 313
 314         if (suppress_report(&data->location))
 315                 return;
 316
 317         val_to_string(from_val_str, sizeof(from_val_str), data->from_type, from_val);
 318         val_to_string(to_val_str, sizeof(to_val_str), data->to_type, to_val);
 319
 320         ubsan_prologue(&data->location, "implicit-conversion");
 321
 322         pr_err("cannot represent %s value %s during %s %s, truncated to %s\n",
 323                 data->from_type->type_name,
 324                 from_val_str,
 325                 type_check_kinds[data->type_check_kind],
 326                 data->to_type->type_name,
 327                 to_val_str);
 328
 329         ubsan_epilogue();
 330 }
 331 EXPORT_SYMBOL(__ubsan_handle_implicit_conversion);
 332
 333 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
 334 {
 335         struct overflow_data *data = _data;
 336         char rhs_val_str[VALUE_LENGTH];
 337
 338         if (suppress_report(&data->location))
 339                 return;
 340
 341         ubsan_prologue(&data->location, "division-overflow");
 342
 343         val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
 344
 345         if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
 346                 pr_err("division of %s by -1 cannot be represented in type %s\n",
 347                         rhs_val_str, data->type->type_name);
 348         else
 349                 pr_err("division by zero\n");
 350
 351         ubsan_epilogue();
 352 }
 353 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
 354
 355 static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
 356 {
 357         if (suppress_report(data->location))
 358                 return;
 359
 360         ubsan_prologue(data->location, "null-ptr-deref");
 361
 362         pr_err("%s null pointer of type %s\n",
 363                 type_check_kinds[data->type_check_kind],
 364                 data->type->type_name);
 365
 366         ubsan_epilogue();
 367 }
 368
 369 static void handle_misaligned_access(struct type_mismatch_data_common *data,
 370                                 unsigned long ptr)
 371 {
 372         if (suppress_report(data->location))
 373                 return;
 374
 375         ubsan_prologue(data->location, "misaligned-access");
 376
 377         pr_err("%s misaligned address %p for type %s\n",
 378                 type_check_kinds[data->type_check_kind],
 379                 (void *)ptr, data->type->type_name);
 380         pr_err("which requires %ld byte alignment\n", data->alignment);
 381
 382         ubsan_epilogue();
 383 }
 384
 385 static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
 386                                         unsigned long ptr)
 387 {
 388         if (suppress_report(data->location))
 389                 return;
 390
 391         ubsan_prologue(data->location, "object-size-mismatch");
 392         pr_err("%s address %p with insufficient space\n",
 393                 type_check_kinds[data->type_check_kind],
 394                 (void *) ptr);
 395         pr_err("for an object of type %s\n", data->type->type_name);
 396         ubsan_epilogue();
 397 }
 398
 399 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
 400                                 unsigned long ptr)
 401 {
 402         unsigned long flags = user_access_save();
 403
 404         if (!ptr)
 405                 handle_null_ptr_deref(data);
 406         else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
 407                 handle_misaligned_access(data, ptr);
 408         else
 409                 handle_object_size_mismatch(data, ptr);
 410
 411         user_access_restore(flags);
 412 }
 413
 414 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
 415                                 void *ptr)
 416 {
 417         struct type_mismatch_data_common common_data = {
 418                 .location = &data->location,
 419                 .type = data->type,
 420                 .alignment = data->alignment,
 421                 .type_check_kind = data->type_check_kind
 422         };
 423
 424         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
 425 }
 426 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
 427
 428 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
 429 {
 430         struct type_mismatch_data_v1 *data = _data;
 431         struct type_mismatch_data_common common_data = {
 432                 .location = &data->location,
 433                 .type = data->type,
 434                 .alignment = 1UL << data->log_alignment,
 435                 .type_check_kind = data->type_check_kind
 436         };
 437
 438         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
 439 }
 440 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
 441
 442 void __ubsan_handle_out_of_bounds(void *_data, void *index)
 443 {
 444         struct out_of_bounds_data *data = _data;
 445         char index_str[VALUE_LENGTH];
 446
 447         if (suppress_report(&data->location))
 448                 return;
 449
 450         ubsan_prologue(&data->location, "array-index-out-of-bounds");
 451
 452         val_to_string(index_str, sizeof(index_str), data->index_type, index);
 453         pr_err("index %s is out of range for type %s\n", index_str,
 454                 data->array_type->type_name);
 455         ubsan_epilogue();
 456 }
 457 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
 458
 459 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
 460 {
 461         struct shift_out_of_bounds_data *data = _data;
 462         struct type_descriptor *rhs_type = data->rhs_type;
 463         struct type_descriptor *lhs_type = data->lhs_type;
 464         char rhs_str[VALUE_LENGTH];
 465         char lhs_str[VALUE_LENGTH];
 466         unsigned long ua_flags = user_access_save();
 467
 468         if (suppress_report(&data->location))
 469                 goto out;
 470
 471         ubsan_prologue(&data->location, "shift-out-of-bounds");
 472
 473         val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
 474         val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
 475
 476         if (val_is_negative(rhs_type, rhs))
 477                 pr_err("shift exponent %s is negative\n", rhs_str);
 478
 479         else if (get_unsigned_val(rhs_type, rhs) >=
 480                 type_bit_width(lhs_type))
 481                 pr_err("shift exponent %s is too large for %u-bit type %s\n",
 482                         rhs_str,
 483                         type_bit_width(lhs_type),
 484                         lhs_type->type_name);
 485         else if (val_is_negative(lhs_type, lhs))
 486                 pr_err("left shift of negative value %s\n",
 487                         lhs_str);
 488         else
 489                 pr_err("left shift of %s by %s places cannot be"
 490                         " represented in type %s\n",
 491                         lhs_str, rhs_str,
 492                         lhs_type->type_name);
 493
 494         ubsan_epilogue();
 495 out:
 496         user_access_restore(ua_flags);
 497 }
 498 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
 499
 500
 501 void __ubsan_handle_builtin_unreachable(void *_data)
 502 {
 503         struct unreachable_data *data = _data;
 504         ubsan_prologue(&data->location, "unreachable");
 505         pr_err("calling __builtin_unreachable()\n");
 506         ubsan_epilogue();
 507         panic("can't return from __builtin_unreachable()");
 508 }
 509 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
 510
 511 void __ubsan_handle_load_invalid_value(void *_data, void *val)
 512 {
 513         struct invalid_value_data *data = _data;
 514         char val_str[VALUE_LENGTH];
 515         unsigned long ua_flags = user_access_save();
 516
 517         if (suppress_report(&data->location))
 518                 goto out;
 519
 520         ubsan_prologue(&data->location, "invalid-load");
 521
 522         val_to_string(val_str, sizeof(val_str), data->type, val);
 523
 524         pr_err("load of value %s is not a valid value for type %s\n",
 525                 val_str, data->type->type_name);
 526
 527         ubsan_epilogue();
 528 out:
 529         user_access_restore(ua_flags);
 530 }
 531 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
 532
 533 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
 534                                          unsigned long align,
 535                                          unsigned long offset)
 536 {
 537         struct alignment_assumption_data *data = _data;
 538         unsigned long real_ptr;
 539
 540         if (suppress_report(&data->location))
 541                 return;
 542
 543         ubsan_prologue(&data->location, "alignment-assumption");
 544
 545         if (offset)
 546                 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
 547                        align, offset, data->type->type_name);
 548         else
 549                 pr_err("assumption of %lu byte alignment for pointer of type %s failed",
 550                        align, data->type->type_name);
 551
 552         real_ptr = ptr - offset;
 553         pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
 554                offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
 555                real_ptr & (align - 1));
 556
 557         ubsan_epilogue();
 558 }
 559 EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);
 560
 561 #endif /* !CONFIG_UBSAN_TRAP */