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 #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, void *val) 91 { 92 if (is_inline_int(type)) { 93 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type); 94 unsigned long ulong_val = (unsigned long)val; 95 96 return ((s_max)ulong_val) << extra_bits >> extra_bits; 97 } 98 99 if (type_bit_width(type) == 64) 100 return *(s64 *)val; 101 102 return *(s_max *)val; 103 } 104 105 static bool val_is_negative(struct type_descriptor *type, void *val) 106 { 107 return type_is_signed(type) && get_signed_val(type, val) < 0; 108 } 109 110 static u_max get_unsigned_val(struct type_descriptor *type, void *val) 111 { 112 if (is_inline_int(type)) 113 return (unsigned long)val; 114 115 if (type_bit_width(type) == 64) 116 return *(u64 *)val; 117 118 return *(u_max *)val; 119 } 120 121 static void val_to_string(char *str, size_t size, struct type_descriptor *type, 122 void *value) 123 { 124 if (type_is_int(type)) { 125 if (type_bit_width(type) == 128) { 126 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__) 127 u_max val = get_unsigned_val(type, value); 128 129 scnprintf(str, size, "0x%08x%08x%08x%08x", 130 (u32)(val >> 96), 131 (u32)(val >> 64), 132 (u32)(val >> 32), 133 (u32)(val)); 134 #else 135 WARN_ON(1); 136 #endif 137 } else if (type_is_signed(type)) { 138 scnprintf(str, size, "%lld", 139 (s64)get_signed_val(type, value)); 140 } else { 141 scnprintf(str, size, "%llu", 142 (u64)get_unsigned_val(type, value)); 143 } 144 } 145 } 146 147 static DEFINE_SPINLOCK(report_lock); 148 149 static void ubsan_prologue(struct source_location *location, 150 unsigned long *flags) 151 { 152 current->in_ubsan++; 153 spin_lock_irqsave(&report_lock, *flags); 154 155 pr_err("========================================" 156 "========================================\n"); 157 print_source_location("UBSAN: Undefined behaviour in", location); 158 } 159 160 static void ubsan_epilogue(unsigned long *flags) 161 { 162 dump_stack(); 163 pr_err("========================================" 164 "========================================\n"); 165 spin_unlock_irqrestore(&report_lock, *flags); 166 current->in_ubsan--; 167 } 168 169 static void handle_overflow(struct overflow_data *data, void *lhs, 170 void *rhs, char op) 171 { 172 173 struct type_descriptor *type = data->type; 174 unsigned long flags; 175 char lhs_val_str[VALUE_LENGTH]; 176 char rhs_val_str[VALUE_LENGTH]; 177 178 if (suppress_report(&data->location)) 179 return; 180 181 ubsan_prologue(&data->location, &flags); 182 183 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); 184 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); 185 pr_err("%s integer overflow:\n", 186 type_is_signed(type) ? "signed" : "unsigned"); 187 pr_err("%s %c %s cannot be represented in type %s\n", 188 lhs_val_str, 189 op, 190 rhs_val_str, 191 type->type_name); 192 193 ubsan_epilogue(&flags); 194 } 195 196 void __ubsan_handle_add_overflow(struct overflow_data *data, 197 void *lhs, void *rhs) 198 { 199 200 handle_overflow(data, lhs, rhs, '+'); 201 } 202 EXPORT_SYMBOL(__ubsan_handle_add_overflow); 203 204 void __ubsan_handle_sub_overflow(struct overflow_data *data, 205 void *lhs, void *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 void *lhs, void *rhs) 213 { 214 handle_overflow(data, lhs, rhs, '*'); 215 } 216 EXPORT_SYMBOL(__ubsan_handle_mul_overflow); 217 218 void __ubsan_handle_negate_overflow(struct overflow_data *data, 219 void *old_val) 220 { 221 unsigned long flags; 222 char old_val_str[VALUE_LENGTH]; 223 224 if (suppress_report(&data->location)) 225 return; 226 227 ubsan_prologue(&data->location, &flags); 228 229 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); 230 231 pr_err("negation of %s cannot be represented in type %s:\n", 232 old_val_str, data->type->type_name); 233 234 ubsan_epilogue(&flags); 235 } 236 EXPORT_SYMBOL(__ubsan_handle_negate_overflow); 237 238 239 void __ubsan_handle_divrem_overflow(struct overflow_data *data, 240 void *lhs, void *rhs) 241 { 242 unsigned long flags; 243 char rhs_val_str[VALUE_LENGTH]; 244 245 if (suppress_report(&data->location)) 246 return; 247 248 ubsan_prologue(&data->location, &flags); 249 250 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 251 252 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 253 pr_err("division of %s by -1 cannot be represented in type %s\n", 254 rhs_val_str, data->type->type_name); 255 else 256 pr_err("division by zero\n"); 257 258 ubsan_epilogue(&flags); 259 } 260 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 261 262 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 263 { 264 unsigned long flags; 265 266 if (suppress_report(data->location)) 267 return; 268 269 ubsan_prologue(data->location, &flags); 270 271 pr_err("%s null pointer of type %s\n", 272 type_check_kinds[data->type_check_kind], 273 data->type->type_name); 274 275 ubsan_epilogue(&flags); 276 } 277 278 static void handle_misaligned_access(struct type_mismatch_data_common *data, 279 unsigned long ptr) 280 { 281 unsigned long flags; 282 283 if (suppress_report(data->location)) 284 return; 285 286 ubsan_prologue(data->location, &flags); 287 288 pr_err("%s misaligned address %p for type %s\n", 289 type_check_kinds[data->type_check_kind], 290 (void *)ptr, data->type->type_name); 291 pr_err("which requires %ld byte alignment\n", data->alignment); 292 293 ubsan_epilogue(&flags); 294 } 295 296 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 297 unsigned long ptr) 298 { 299 unsigned long flags; 300 301 if (suppress_report(data->location)) 302 return; 303 304 ubsan_prologue(data->location, &flags); 305 pr_err("%s address %p with insufficient space\n", 306 type_check_kinds[data->type_check_kind], 307 (void *) ptr); 308 pr_err("for an object of type %s\n", data->type->type_name); 309 ubsan_epilogue(&flags); 310 } 311 312 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 313 unsigned long ptr) 314 { 315 unsigned long flags = user_access_save(); 316 317 if (!ptr) 318 handle_null_ptr_deref(data); 319 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 320 handle_misaligned_access(data, ptr); 321 else 322 handle_object_size_mismatch(data, ptr); 323 324 user_access_restore(flags); 325 } 326 327 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 328 void *ptr) 329 { 330 struct type_mismatch_data_common common_data = { 331 .location = &data->location, 332 .type = data->type, 333 .alignment = data->alignment, 334 .type_check_kind = data->type_check_kind 335 }; 336 337 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 338 } 339 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 340 341 void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data, 342 void *ptr) 343 { 344 345 struct type_mismatch_data_common common_data = { 346 .location = &data->location, 347 .type = data->type, 348 .alignment = 1UL << data->log_alignment, 349 .type_check_kind = data->type_check_kind 350 }; 351 352 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 353 } 354 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 355 356 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index) 357 { 358 unsigned long flags; 359 char index_str[VALUE_LENGTH]; 360 361 if (suppress_report(&data->location)) 362 return; 363 364 ubsan_prologue(&data->location, &flags); 365 366 val_to_string(index_str, sizeof(index_str), data->index_type, index); 367 pr_err("index %s is out of range for type %s\n", index_str, 368 data->array_type->type_name); 369 ubsan_epilogue(&flags); 370 } 371 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 372 373 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, 374 void *lhs, void *rhs) 375 { 376 unsigned long flags; 377 struct type_descriptor *rhs_type = data->rhs_type; 378 struct type_descriptor *lhs_type = data->lhs_type; 379 char rhs_str[VALUE_LENGTH]; 380 char lhs_str[VALUE_LENGTH]; 381 382 if (suppress_report(&data->location)) 383 return; 384 385 ubsan_prologue(&data->location, &flags); 386 387 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 388 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 389 390 if (val_is_negative(rhs_type, rhs)) 391 pr_err("shift exponent %s is negative\n", rhs_str); 392 393 else if (get_unsigned_val(rhs_type, rhs) >= 394 type_bit_width(lhs_type)) 395 pr_err("shift exponent %s is too large for %u-bit type %s\n", 396 rhs_str, 397 type_bit_width(lhs_type), 398 lhs_type->type_name); 399 else if (val_is_negative(lhs_type, lhs)) 400 pr_err("left shift of negative value %s\n", 401 lhs_str); 402 else 403 pr_err("left shift of %s by %s places cannot be" 404 " represented in type %s\n", 405 lhs_str, rhs_str, 406 lhs_type->type_name); 407 408 ubsan_epilogue(&flags); 409 } 410 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 411 412 413 void __ubsan_handle_builtin_unreachable(struct unreachable_data *data) 414 { 415 unsigned long flags; 416 417 ubsan_prologue(&data->location, &flags); 418 pr_err("calling __builtin_unreachable()\n"); 419 ubsan_epilogue(&flags); 420 panic("can't return from __builtin_unreachable()"); 421 } 422 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 423 424 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data, 425 void *val) 426 { 427 unsigned long flags; 428 char val_str[VALUE_LENGTH]; 429 430 if (suppress_report(&data->location)) 431 return; 432 433 ubsan_prologue(&data->location, &flags); 434 435 val_to_string(val_str, sizeof(val_str), data->type, val); 436 437 pr_err("load of value %s is not a valid value for type %s\n", 438 val_str, data->type->type_name); 439 440 ubsan_epilogue(&flags); 441 } 442 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 443