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