1 /* 2 * UBSAN error reporting functions 3 * 4 * Copyright (c) 2014 Samsung Electronics Co., Ltd. 5 * Author: Andrey Ryabinin <[email protected]> 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 #include <linux/uaccess.h> 21 22 #include "ubsan.h" 23 24 const char *type_check_kinds[] = { 25 "load of", 26 "store to", 27 "reference binding to", 28 "member access within", 29 "member call on", 30 "constructor call on", 31 "downcast of", 32 "downcast of" 33 }; 34 35 #define REPORTED_BIT 31 36 37 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN) 38 #define COLUMN_MASK (~(1U << REPORTED_BIT)) 39 #define LINE_MASK (~0U) 40 #else 41 #define COLUMN_MASK (~0U) 42 #define LINE_MASK (~(1U << REPORTED_BIT)) 43 #endif 44 45 #define VALUE_LENGTH 40 46 47 static bool was_reported(struct source_location *location) 48 { 49 return test_and_set_bit(REPORTED_BIT, &location->reported); 50 } 51 52 static void print_source_location(const char *prefix, 53 struct source_location *loc) 54 { 55 pr_err("%s %s:%d:%d\n", prefix, loc->file_name, 56 loc->line & LINE_MASK, loc->column & COLUMN_MASK); 57 } 58 59 static bool suppress_report(struct source_location *loc) 60 { 61 return current->in_ubsan || was_reported(loc); 62 } 63 64 static bool type_is_int(struct type_descriptor *type) 65 { 66 return type->type_kind == type_kind_int; 67 } 68 69 static bool type_is_signed(struct type_descriptor *type) 70 { 71 WARN_ON(!type_is_int(type)); 72 return type->type_info & 1; 73 } 74 75 static unsigned type_bit_width(struct type_descriptor *type) 76 { 77 return 1 << (type->type_info >> 1); 78 } 79 80 static bool is_inline_int(struct type_descriptor *type) 81 { 82 unsigned inline_bits = sizeof(unsigned long)*8; 83 unsigned bits = type_bit_width(type); 84 85 WARN_ON(!type_is_int(type)); 86 87 return bits <= inline_bits; 88 } 89 90 static s_max get_signed_val(struct type_descriptor *type, unsigned long val) 91 { 92 if (is_inline_int(type)) { 93 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type); 94 return ((s_max)val) << extra_bits >> extra_bits; 95 } 96 97 if (type_bit_width(type) == 64) 98 return *(s64 *)val; 99 100 return *(s_max *)val; 101 } 102 103 static bool val_is_negative(struct type_descriptor *type, unsigned long val) 104 { 105 return type_is_signed(type) && get_signed_val(type, val) < 0; 106 } 107 108 static u_max get_unsigned_val(struct type_descriptor *type, unsigned long val) 109 { 110 if (is_inline_int(type)) 111 return val; 112 113 if (type_bit_width(type) == 64) 114 return *(u64 *)val; 115 116 return *(u_max *)val; 117 } 118 119 static void val_to_string(char *str, size_t size, struct type_descriptor *type, 120 unsigned long value) 121 { 122 if (type_is_int(type)) { 123 if (type_bit_width(type) == 128) { 124 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__) 125 u_max val = get_unsigned_val(type, value); 126 127 scnprintf(str, size, "0x%08x%08x%08x%08x", 128 (u32)(val >> 96), 129 (u32)(val >> 64), 130 (u32)(val >> 32), 131 (u32)(val)); 132 #else 133 WARN_ON(1); 134 #endif 135 } else if (type_is_signed(type)) { 136 scnprintf(str, size, "%lld", 137 (s64)get_signed_val(type, value)); 138 } else { 139 scnprintf(str, size, "%llu", 140 (u64)get_unsigned_val(type, value)); 141 } 142 } 143 } 144 145 static DEFINE_SPINLOCK(report_lock); 146 147 static void ubsan_prologue(struct source_location *location, 148 unsigned long *flags) 149 { 150 current->in_ubsan++; 151 spin_lock_irqsave(&report_lock, *flags); 152 153 pr_err("========================================" 154 "========================================\n"); 155 print_source_location("UBSAN: Undefined behaviour in", location); 156 } 157 158 static void ubsan_epilogue(unsigned long *flags) 159 { 160 dump_stack(); 161 pr_err("========================================" 162 "========================================\n"); 163 spin_unlock_irqrestore(&report_lock, *flags); 164 current->in_ubsan--; 165 } 166 167 static void handle_overflow(struct overflow_data *data, unsigned long lhs, 168 unsigned long rhs, char op) 169 { 170 171 struct type_descriptor *type = data->type; 172 unsigned long flags; 173 char lhs_val_str[VALUE_LENGTH]; 174 char rhs_val_str[VALUE_LENGTH]; 175 176 if (suppress_report(&data->location)) 177 return; 178 179 ubsan_prologue(&data->location, &flags); 180 181 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); 182 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); 183 pr_err("%s integer overflow:\n", 184 type_is_signed(type) ? "signed" : "unsigned"); 185 pr_err("%s %c %s cannot be represented in type %s\n", 186 lhs_val_str, 187 op, 188 rhs_val_str, 189 type->type_name); 190 191 ubsan_epilogue(&flags); 192 } 193 194 void __ubsan_handle_add_overflow(struct overflow_data *data, 195 unsigned long lhs, 196 unsigned long 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 unsigned long lhs, 205 unsigned long rhs) 206 { 207 handle_overflow(data, lhs, rhs, '-'); 208 } 209 EXPORT_SYMBOL(__ubsan_handle_sub_overflow); 210 211 void __ubsan_handle_mul_overflow(struct overflow_data *data, 212 unsigned long lhs, 213 unsigned long rhs) 214 { 215 handle_overflow(data, lhs, rhs, '*'); 216 } 217 EXPORT_SYMBOL(__ubsan_handle_mul_overflow); 218 219 void __ubsan_handle_negate_overflow(struct overflow_data *data, 220 unsigned long old_val) 221 { 222 unsigned long flags; 223 char old_val_str[VALUE_LENGTH]; 224 225 if (suppress_report(&data->location)) 226 return; 227 228 ubsan_prologue(&data->location, &flags); 229 230 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); 231 232 pr_err("negation of %s cannot be represented in type %s:\n", 233 old_val_str, data->type->type_name); 234 235 ubsan_epilogue(&flags); 236 } 237 EXPORT_SYMBOL(__ubsan_handle_negate_overflow); 238 239 240 void __ubsan_handle_divrem_overflow(struct overflow_data *data, 241 unsigned long lhs, 242 unsigned long rhs) 243 { 244 unsigned long flags; 245 char rhs_val_str[VALUE_LENGTH]; 246 247 if (suppress_report(&data->location)) 248 return; 249 250 ubsan_prologue(&data->location, &flags); 251 252 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 253 254 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 255 pr_err("division of %s by -1 cannot be represented in type %s\n", 256 rhs_val_str, data->type->type_name); 257 else 258 pr_err("division by zero\n"); 259 260 ubsan_epilogue(&flags); 261 } 262 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 263 264 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 265 { 266 unsigned long flags; 267 268 if (suppress_report(data->location)) 269 return; 270 271 ubsan_prologue(data->location, &flags); 272 273 pr_err("%s null pointer of type %s\n", 274 type_check_kinds[data->type_check_kind], 275 data->type->type_name); 276 277 ubsan_epilogue(&flags); 278 } 279 280 static void handle_misaligned_access(struct type_mismatch_data_common *data, 281 unsigned long ptr) 282 { 283 unsigned long flags; 284 285 if (suppress_report(data->location)) 286 return; 287 288 ubsan_prologue(data->location, &flags); 289 290 pr_err("%s misaligned address %p for type %s\n", 291 type_check_kinds[data->type_check_kind], 292 (void *)ptr, data->type->type_name); 293 pr_err("which requires %ld byte alignment\n", data->alignment); 294 295 ubsan_epilogue(&flags); 296 } 297 298 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 299 unsigned long ptr) 300 { 301 unsigned long flags; 302 303 if (suppress_report(data->location)) 304 return; 305 306 ubsan_prologue(data->location, &flags); 307 pr_err("%s address %p with insufficient space\n", 308 type_check_kinds[data->type_check_kind], 309 (void *) ptr); 310 pr_err("for an object of type %s\n", data->type->type_name); 311 ubsan_epilogue(&flags); 312 } 313 314 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 315 unsigned long ptr) 316 { 317 unsigned long flags = user_access_save(); 318 319 if (!ptr) 320 handle_null_ptr_deref(data); 321 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 322 handle_misaligned_access(data, ptr); 323 else 324 handle_object_size_mismatch(data, ptr); 325 326 user_access_restore(flags); 327 } 328 329 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 330 unsigned long ptr) 331 { 332 struct type_mismatch_data_common common_data = { 333 .location = &data->location, 334 .type = data->type, 335 .alignment = data->alignment, 336 .type_check_kind = data->type_check_kind 337 }; 338 339 ubsan_type_mismatch_common(&common_data, ptr); 340 } 341 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 342 343 void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data, 344 unsigned long ptr) 345 { 346 347 struct type_mismatch_data_common common_data = { 348 .location = &data->location, 349 .type = data->type, 350 .alignment = 1UL << data->log_alignment, 351 .type_check_kind = data->type_check_kind 352 }; 353 354 ubsan_type_mismatch_common(&common_data, ptr); 355 } 356 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 357 358 void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data, 359 unsigned long bound) 360 { 361 unsigned long flags; 362 char bound_str[VALUE_LENGTH]; 363 364 if (suppress_report(&data->location)) 365 return; 366 367 ubsan_prologue(&data->location, &flags); 368 369 val_to_string(bound_str, sizeof(bound_str), data->type, bound); 370 pr_err("variable length array bound value %s <= 0\n", bound_str); 371 372 ubsan_epilogue(&flags); 373 } 374 EXPORT_SYMBOL(__ubsan_handle_vla_bound_not_positive); 375 376 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, 377 unsigned long index) 378 { 379 unsigned long flags; 380 char index_str[VALUE_LENGTH]; 381 382 if (suppress_report(&data->location)) 383 return; 384 385 ubsan_prologue(&data->location, &flags); 386 387 val_to_string(index_str, sizeof(index_str), data->index_type, index); 388 pr_err("index %s is out of range for type %s\n", index_str, 389 data->array_type->type_name); 390 ubsan_epilogue(&flags); 391 } 392 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 393 394 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, 395 unsigned long lhs, unsigned long rhs) 396 { 397 unsigned long flags; 398 struct type_descriptor *rhs_type = data->rhs_type; 399 struct type_descriptor *lhs_type = data->lhs_type; 400 char rhs_str[VALUE_LENGTH]; 401 char lhs_str[VALUE_LENGTH]; 402 403 if (suppress_report(&data->location)) 404 return; 405 406 ubsan_prologue(&data->location, &flags); 407 408 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 409 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 410 411 if (val_is_negative(rhs_type, rhs)) 412 pr_err("shift exponent %s is negative\n", rhs_str); 413 414 else if (get_unsigned_val(rhs_type, rhs) >= 415 type_bit_width(lhs_type)) 416 pr_err("shift exponent %s is too large for %u-bit type %s\n", 417 rhs_str, 418 type_bit_width(lhs_type), 419 lhs_type->type_name); 420 else if (val_is_negative(lhs_type, lhs)) 421 pr_err("left shift of negative value %s\n", 422 lhs_str); 423 else 424 pr_err("left shift of %s by %s places cannot be" 425 " represented in type %s\n", 426 lhs_str, rhs_str, 427 lhs_type->type_name); 428 429 ubsan_epilogue(&flags); 430 } 431 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 432 433 434 void __ubsan_handle_builtin_unreachable(struct unreachable_data *data) 435 { 436 unsigned long flags; 437 438 ubsan_prologue(&data->location, &flags); 439 pr_err("calling __builtin_unreachable()\n"); 440 ubsan_epilogue(&flags); 441 panic("can't return from __builtin_unreachable()"); 442 } 443 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 444 445 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data, 446 unsigned long val) 447 { 448 unsigned long flags; 449 char val_str[VALUE_LENGTH]; 450 451 if (suppress_report(&data->location)) 452 return; 453 454 ubsan_prologue(&data->location, &flags); 455 456 val_to_string(val_str, sizeof(val_str), data->type, val); 457 458 pr_err("load of value %s is not a valid value for type %s\n", 459 val_str, data->type->type_name); 460 461 ubsan_epilogue(&flags); 462 } 463 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 464