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) 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 void ubsan_prologue(struct source_location *location) 144 { 145 current->in_ubsan++; 146 147 pr_err("========================================" 148 "========================================\n"); 149 print_source_location("UBSAN: Undefined behaviour in", location); 150 } 151 152 static void ubsan_epilogue(void) 153 { 154 dump_stack(); 155 pr_err("========================================" 156 "========================================\n"); 157 158 current->in_ubsan--; 159 } 160 161 static void handle_overflow(struct overflow_data *data, void *lhs, 162 void *rhs, char op) 163 { 164 165 struct type_descriptor *type = data->type; 166 char lhs_val_str[VALUE_LENGTH]; 167 char rhs_val_str[VALUE_LENGTH]; 168 169 if (suppress_report(&data->location)) 170 return; 171 172 ubsan_prologue(&data->location); 173 174 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); 175 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); 176 pr_err("%s integer overflow:\n", 177 type_is_signed(type) ? "signed" : "unsigned"); 178 pr_err("%s %c %s cannot be represented in type %s\n", 179 lhs_val_str, 180 op, 181 rhs_val_str, 182 type->type_name); 183 184 ubsan_epilogue(); 185 } 186 187 void __ubsan_handle_add_overflow(struct overflow_data *data, 188 void *lhs, void *rhs) 189 { 190 191 handle_overflow(data, lhs, rhs, '+'); 192 } 193 EXPORT_SYMBOL(__ubsan_handle_add_overflow); 194 195 void __ubsan_handle_sub_overflow(struct overflow_data *data, 196 void *lhs, void *rhs) 197 { 198 handle_overflow(data, lhs, rhs, '-'); 199 } 200 EXPORT_SYMBOL(__ubsan_handle_sub_overflow); 201 202 void __ubsan_handle_mul_overflow(struct overflow_data *data, 203 void *lhs, void *rhs) 204 { 205 handle_overflow(data, lhs, rhs, '*'); 206 } 207 EXPORT_SYMBOL(__ubsan_handle_mul_overflow); 208 209 void __ubsan_handle_negate_overflow(struct overflow_data *data, 210 void *old_val) 211 { 212 char old_val_str[VALUE_LENGTH]; 213 214 if (suppress_report(&data->location)) 215 return; 216 217 ubsan_prologue(&data->location); 218 219 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); 220 221 pr_err("negation of %s cannot be represented in type %s:\n", 222 old_val_str, data->type->type_name); 223 224 ubsan_epilogue(); 225 } 226 EXPORT_SYMBOL(__ubsan_handle_negate_overflow); 227 228 229 void __ubsan_handle_divrem_overflow(struct overflow_data *data, 230 void *lhs, void *rhs) 231 { 232 char rhs_val_str[VALUE_LENGTH]; 233 234 if (suppress_report(&data->location)) 235 return; 236 237 ubsan_prologue(&data->location); 238 239 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 240 241 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 242 pr_err("division of %s by -1 cannot be represented in type %s\n", 243 rhs_val_str, data->type->type_name); 244 else 245 pr_err("division by zero\n"); 246 247 ubsan_epilogue(); 248 } 249 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 250 251 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 252 { 253 if (suppress_report(data->location)) 254 return; 255 256 ubsan_prologue(data->location); 257 258 pr_err("%s null pointer of type %s\n", 259 type_check_kinds[data->type_check_kind], 260 data->type->type_name); 261 262 ubsan_epilogue(); 263 } 264 265 static void handle_misaligned_access(struct type_mismatch_data_common *data, 266 unsigned long ptr) 267 { 268 if (suppress_report(data->location)) 269 return; 270 271 ubsan_prologue(data->location); 272 273 pr_err("%s misaligned address %p for type %s\n", 274 type_check_kinds[data->type_check_kind], 275 (void *)ptr, data->type->type_name); 276 pr_err("which requires %ld byte alignment\n", data->alignment); 277 278 ubsan_epilogue(); 279 } 280 281 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 282 unsigned long ptr) 283 { 284 if (suppress_report(data->location)) 285 return; 286 287 ubsan_prologue(data->location); 288 pr_err("%s address %p with insufficient space\n", 289 type_check_kinds[data->type_check_kind], 290 (void *) ptr); 291 pr_err("for an object of type %s\n", data->type->type_name); 292 ubsan_epilogue(); 293 } 294 295 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 296 unsigned long ptr) 297 { 298 unsigned long flags = user_access_save(); 299 300 if (!ptr) 301 handle_null_ptr_deref(data); 302 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 303 handle_misaligned_access(data, ptr); 304 else 305 handle_object_size_mismatch(data, ptr); 306 307 user_access_restore(flags); 308 } 309 310 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 311 void *ptr) 312 { 313 struct type_mismatch_data_common common_data = { 314 .location = &data->location, 315 .type = data->type, 316 .alignment = data->alignment, 317 .type_check_kind = data->type_check_kind 318 }; 319 320 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 321 } 322 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 323 324 void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data, 325 void *ptr) 326 { 327 328 struct type_mismatch_data_common common_data = { 329 .location = &data->location, 330 .type = data->type, 331 .alignment = 1UL << data->log_alignment, 332 .type_check_kind = data->type_check_kind 333 }; 334 335 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 336 } 337 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 338 339 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index) 340 { 341 char index_str[VALUE_LENGTH]; 342 343 if (suppress_report(&data->location)) 344 return; 345 346 ubsan_prologue(&data->location); 347 348 val_to_string(index_str, sizeof(index_str), data->index_type, index); 349 pr_err("index %s is out of range for type %s\n", index_str, 350 data->array_type->type_name); 351 ubsan_epilogue(); 352 } 353 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 354 355 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, 356 void *lhs, void *rhs) 357 { 358 struct type_descriptor *rhs_type = data->rhs_type; 359 struct type_descriptor *lhs_type = data->lhs_type; 360 char rhs_str[VALUE_LENGTH]; 361 char lhs_str[VALUE_LENGTH]; 362 unsigned long ua_flags = user_access_save(); 363 364 if (suppress_report(&data->location)) 365 goto out; 366 367 ubsan_prologue(&data->location); 368 369 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 370 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 371 372 if (val_is_negative(rhs_type, rhs)) 373 pr_err("shift exponent %s is negative\n", rhs_str); 374 375 else if (get_unsigned_val(rhs_type, rhs) >= 376 type_bit_width(lhs_type)) 377 pr_err("shift exponent %s is too large for %u-bit type %s\n", 378 rhs_str, 379 type_bit_width(lhs_type), 380 lhs_type->type_name); 381 else if (val_is_negative(lhs_type, lhs)) 382 pr_err("left shift of negative value %s\n", 383 lhs_str); 384 else 385 pr_err("left shift of %s by %s places cannot be" 386 " represented in type %s\n", 387 lhs_str, rhs_str, 388 lhs_type->type_name); 389 390 ubsan_epilogue(); 391 out: 392 user_access_restore(ua_flags); 393 } 394 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 395 396 397 void __ubsan_handle_builtin_unreachable(struct unreachable_data *data) 398 { 399 ubsan_prologue(&data->location); 400 pr_err("calling __builtin_unreachable()\n"); 401 ubsan_epilogue(); 402 panic("can't return from __builtin_unreachable()"); 403 } 404 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 405 406 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data, 407 void *val) 408 { 409 char val_str[VALUE_LENGTH]; 410 411 if (suppress_report(&data->location)) 412 return; 413 414 ubsan_prologue(&data->location); 415 416 val_to_string(val_str, sizeof(val_str), data->type, val); 417 418 pr_err("load of value %s is not a valid value for type %s\n", 419 val_str, data->type->type_name); 420 421 ubsan_epilogue(); 422 } 423 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 424