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 #ifdef CONFIG_UBSAN_TRAP
  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(struct pt_regs *regs, 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_SIGNED_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_SIGNED_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 #else
 101 static const char * const type_check_kinds[] = {
 102         "load of",
 103         "store to",
 104         "reference binding to",
 105         "member access within",
 106         "member call on",
 107         "constructor call on",
 108         "downcast of",
 109         "downcast of"
 110 };
 111
 112 #define REPORTED_BIT 31
 113
 114 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
 115 #define COLUMN_MASK (~(1U << REPORTED_BIT))
 116 #define LINE_MASK   (~0U)
 117 #else
 118 #define COLUMN_MASK   (~0U)
 119 #define LINE_MASK (~(1U << REPORTED_BIT))
 120 #endif
 121
 122 #define VALUE_LENGTH 40
 123
 124 static bool was_reported(struct source_location *location)
 125 {
 126         return test_and_set_bit(REPORTED_BIT, &location->reported);
 127 }
 128
 129 static bool suppress_report(struct source_location *loc)
 130 {
 131         return current->in_ubsan || was_reported(loc);
 132 }
 133
 134 static bool type_is_int(struct type_descriptor *type)
 135 {
 136         return type->type_kind == type_kind_int;
 137 }
 138
 139 static bool type_is_signed(struct type_descriptor *type)
 140 {
 141         WARN_ON(!type_is_int(type));
 142         return  type->type_info & 1;
 143 }
 144
 145 static unsigned type_bit_width(struct type_descriptor *type)
 146 {
 147         return 1 << (type->type_info >> 1);
 148 }
 149
 150 static bool is_inline_int(struct type_descriptor *type)
 151 {
 152         unsigned inline_bits = sizeof(unsigned long)*8;
 153         unsigned bits = type_bit_width(type);
 154
 155         WARN_ON(!type_is_int(type));
 156
 157         return bits <= inline_bits;
 158 }
 159
 160 static s_max get_signed_val(struct type_descriptor *type, void *val)
 161 {
 162         if (is_inline_int(type)) {
 163                 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
 164                 unsigned long ulong_val = (unsigned long)val;
 165
 166                 return ((s_max)ulong_val) << extra_bits >> extra_bits;
 167         }
 168
 169         if (type_bit_width(type) == 64)
 170                 return *(s64 *)val;
 171
 172         return *(s_max *)val;
 173 }
 174
 175 static bool val_is_negative(struct type_descriptor *type, void *val)
 176 {
 177         return type_is_signed(type) && get_signed_val(type, val) < 0;
 178 }
 179
 180 static u_max get_unsigned_val(struct type_descriptor *type, void *val)
 181 {
 182         if (is_inline_int(type))
 183                 return (unsigned long)val;
 184
 185         if (type_bit_width(type) == 64)
 186                 return *(u64 *)val;
 187
 188         return *(u_max *)val;
 189 }
 190
 191 static void val_to_string(char *str, size_t size, struct type_descriptor *type,
 192                         void *value)
 193 {
 194         if (type_is_int(type)) {
 195                 if (type_bit_width(type) == 128) {
 196 #if defined(CONFIG_ARCH_SUPPORTS_INT128)
 197                         u_max val = get_unsigned_val(type, value);
 198
 199                         scnprintf(str, size, "0x%08x%08x%08x%08x",
 200                                 (u32)(val >> 96),
 201                                 (u32)(val >> 64),
 202                                 (u32)(val >> 32),
 203                                 (u32)(val));
 204 #else
 205                         WARN_ON(1);
 206 #endif
 207                 } else if (type_is_signed(type)) {
 208                         scnprintf(str, size, "%lld",
 209                                 (s64)get_signed_val(type, value));
 210                 } else {
 211                         scnprintf(str, size, "%llu",
 212                                 (u64)get_unsigned_val(type, value));
 213                 }
 214         }
 215 }
 216
 217 static void ubsan_prologue(struct source_location *loc, const char *reason)
 218 {
 219         current->in_ubsan++;
 220
 221         pr_warn(CUT_HERE);
 222
 223         pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
 224                 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
 225
 226         kunit_fail_current_test("%s in %s", reason, loc->file_name);
 227 }
 228
 229 static void ubsan_epilogue(void)
 230 {
 231         dump_stack();
 232         pr_warn("---[ end trace ]---\n");
 233
 234         current->in_ubsan--;
 235
 236         check_panic_on_warn("UBSAN");
 237 }
 238
 239 static void handle_overflow(struct overflow_data *data, void *lhs,
 240                         void *rhs, char op)
 241 {
 242
 243         struct type_descriptor *type = data->type;
 244         char lhs_val_str[VALUE_LENGTH];
 245         char rhs_val_str[VALUE_LENGTH];
 246
 247         if (suppress_report(&data->location))
 248                 return;
 249
 250         ubsan_prologue(&data->location, type_is_signed(type) ?
 251                         "signed-integer-overflow" :
 252                         "unsigned-integer-overflow");
 253
 254         val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
 255         val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
 256         pr_err("%s %c %s cannot be represented in type %s\n",
 257                 lhs_val_str,
 258                 op,
 259                 rhs_val_str,
 260                 type->type_name);
 261
 262         ubsan_epilogue();
 263 }
 264
 265 void __ubsan_handle_add_overflow(void *data,
 266                                 void *lhs, void *rhs)
 267 {
 268
 269         handle_overflow(data, lhs, rhs, '+');
 270 }
 271 EXPORT_SYMBOL(__ubsan_handle_add_overflow);
 272
 273 void __ubsan_handle_sub_overflow(void *data,
 274                                 void *lhs, void *rhs)
 275 {
 276         handle_overflow(data, lhs, rhs, '-');
 277 }
 278 EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
 279
 280 void __ubsan_handle_mul_overflow(void *data,
 281                                 void *lhs, void *rhs)
 282 {
 283         handle_overflow(data, lhs, rhs, '*');
 284 }
 285 EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
 286
 287 void __ubsan_handle_negate_overflow(void *_data, void *old_val)
 288 {
 289         struct overflow_data *data = _data;
 290         char old_val_str[VALUE_LENGTH];
 291
 292         if (suppress_report(&data->location))
 293                 return;
 294
 295         ubsan_prologue(&data->location, "negation-overflow");
 296
 297         val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
 298
 299         pr_err("negation of %s cannot be represented in type %s:\n",
 300                 old_val_str, data->type->type_name);
 301
 302         ubsan_epilogue();
 303 }
 304 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
 305
 306
 307 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
 308 {
 309         struct overflow_data *data = _data;
 310         char rhs_val_str[VALUE_LENGTH];
 311
 312         if (suppress_report(&data->location))
 313                 return;
 314
 315         ubsan_prologue(&data->location, "division-overflow");
 316
 317         val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
 318
 319         if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
 320                 pr_err("division of %s by -1 cannot be represented in type %s\n",
 321                         rhs_val_str, data->type->type_name);
 322         else
 323                 pr_err("division by zero\n");
 324
 325         ubsan_epilogue();
 326 }
 327 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
 328
 329 static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
 330 {
 331         if (suppress_report(data->location))
 332                 return;
 333
 334         ubsan_prologue(data->location, "null-ptr-deref");
 335
 336         pr_err("%s null pointer of type %s\n",
 337                 type_check_kinds[data->type_check_kind],
 338                 data->type->type_name);
 339
 340         ubsan_epilogue();
 341 }
 342
 343 static void handle_misaligned_access(struct type_mismatch_data_common *data,
 344                                 unsigned long ptr)
 345 {
 346         if (suppress_report(data->location))
 347                 return;
 348
 349         ubsan_prologue(data->location, "misaligned-access");
 350
 351         pr_err("%s misaligned address %p for type %s\n",
 352                 type_check_kinds[data->type_check_kind],
 353                 (void *)ptr, data->type->type_name);
 354         pr_err("which requires %ld byte alignment\n", data->alignment);
 355
 356         ubsan_epilogue();
 357 }
 358
 359 static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
 360                                         unsigned long ptr)
 361 {
 362         if (suppress_report(data->location))
 363                 return;
 364
 365         ubsan_prologue(data->location, "object-size-mismatch");
 366         pr_err("%s address %p with insufficient space\n",
 367                 type_check_kinds[data->type_check_kind],
 368                 (void *) ptr);
 369         pr_err("for an object of type %s\n", data->type->type_name);
 370         ubsan_epilogue();
 371 }
 372
 373 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
 374                                 unsigned long ptr)
 375 {
 376         unsigned long flags = user_access_save();
 377
 378         if (!ptr)
 379                 handle_null_ptr_deref(data);
 380         else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
 381                 handle_misaligned_access(data, ptr);
 382         else
 383                 handle_object_size_mismatch(data, ptr);
 384
 385         user_access_restore(flags);
 386 }
 387
 388 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
 389                                 void *ptr)
 390 {
 391         struct type_mismatch_data_common common_data = {
 392                 .location = &data->location,
 393                 .type = data->type,
 394                 .alignment = data->alignment,
 395                 .type_check_kind = data->type_check_kind
 396         };
 397
 398         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
 399 }
 400 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
 401
 402 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
 403 {
 404         struct type_mismatch_data_v1 *data = _data;
 405         struct type_mismatch_data_common common_data = {
 406                 .location = &data->location,
 407                 .type = data->type,
 408                 .alignment = 1UL << data->log_alignment,
 409                 .type_check_kind = data->type_check_kind
 410         };
 411
 412         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
 413 }
 414 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
 415
 416 void __ubsan_handle_out_of_bounds(void *_data, void *index)
 417 {
 418         struct out_of_bounds_data *data = _data;
 419         char index_str[VALUE_LENGTH];
 420
 421         if (suppress_report(&data->location))
 422                 return;
 423
 424         ubsan_prologue(&data->location, "array-index-out-of-bounds");
 425
 426         val_to_string(index_str, sizeof(index_str), data->index_type, index);
 427         pr_err("index %s is out of range for type %s\n", index_str,
 428                 data->array_type->type_name);
 429         ubsan_epilogue();
 430 }
 431 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
 432
 433 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
 434 {
 435         struct shift_out_of_bounds_data *data = _data;
 436         struct type_descriptor *rhs_type = data->rhs_type;
 437         struct type_descriptor *lhs_type = data->lhs_type;
 438         char rhs_str[VALUE_LENGTH];
 439         char lhs_str[VALUE_LENGTH];
 440         unsigned long ua_flags = user_access_save();
 441
 442         if (suppress_report(&data->location))
 443                 goto out;
 444
 445         ubsan_prologue(&data->location, "shift-out-of-bounds");
 446
 447         val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
 448         val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
 449
 450         if (val_is_negative(rhs_type, rhs))
 451                 pr_err("shift exponent %s is negative\n", rhs_str);
 452
 453         else if (get_unsigned_val(rhs_type, rhs) >=
 454                 type_bit_width(lhs_type))
 455                 pr_err("shift exponent %s is too large for %u-bit type %s\n",
 456                         rhs_str,
 457                         type_bit_width(lhs_type),
 458                         lhs_type->type_name);
 459         else if (val_is_negative(lhs_type, lhs))
 460                 pr_err("left shift of negative value %s\n",
 461                         lhs_str);
 462         else
 463                 pr_err("left shift of %s by %s places cannot be"
 464                         " represented in type %s\n",
 465                         lhs_str, rhs_str,
 466                         lhs_type->type_name);
 467
 468         ubsan_epilogue();
 469 out:
 470         user_access_restore(ua_flags);
 471 }
 472 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
 473
 474
 475 void __ubsan_handle_builtin_unreachable(void *_data)
 476 {
 477         struct unreachable_data *data = _data;
 478         ubsan_prologue(&data->location, "unreachable");
 479         pr_err("calling __builtin_unreachable()\n");
 480         ubsan_epilogue();
 481         panic("can't return from __builtin_unreachable()");
 482 }
 483 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
 484
 485 void __ubsan_handle_load_invalid_value(void *_data, void *val)
 486 {
 487         struct invalid_value_data *data = _data;
 488         char val_str[VALUE_LENGTH];
 489         unsigned long ua_flags = user_access_save();
 490
 491         if (suppress_report(&data->location))
 492                 goto out;
 493
 494         ubsan_prologue(&data->location, "invalid-load");
 495
 496         val_to_string(val_str, sizeof(val_str), data->type, val);
 497
 498         pr_err("load of value %s is not a valid value for type %s\n",
 499                 val_str, data->type->type_name);
 500
 501         ubsan_epilogue();
 502 out:
 503         user_access_restore(ua_flags);
 504 }
 505 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
 506
 507 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
 508                                          unsigned long align,
 509                                          unsigned long offset)
 510 {
 511         struct alignment_assumption_data *data = _data;
 512         unsigned long real_ptr;
 513
 514         if (suppress_report(&data->location))
 515                 return;
 516
 517         ubsan_prologue(&data->location, "alignment-assumption");
 518
 519         if (offset)
 520                 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
 521                        align, offset, data->type->type_name);
 522         else
 523                 pr_err("assumption of %lu byte alignment for pointer of type %s failed",
 524                        align, data->type->type_name);
 525
 526         real_ptr = ptr - offset;
 527         pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
 528                offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
 529                real_ptr & (align - 1));
 530
 531         ubsan_epilogue();
 532 }
 533 EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);
 534
 535 #endif /* !CONFIG_UBSAN_TRAP */