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 bool suppress_report(struct source_location *loc) 49 { 50 return current->in_ubsan || was_reported(loc); 51 } 52 53 static bool type_is_int(struct type_descriptor *type) 54 { 55 return type->type_kind == type_kind_int; 56 } 57 58 static bool type_is_signed(struct type_descriptor *type) 59 { 60 WARN_ON(!type_is_int(type)); 61 return type->type_info & 1; 62 } 63 64 static unsigned type_bit_width(struct type_descriptor *type) 65 { 66 return 1 << (type->type_info >> 1); 67 } 68 69 static bool is_inline_int(struct type_descriptor *type) 70 { 71 unsigned inline_bits = sizeof(unsigned long)*8; 72 unsigned bits = type_bit_width(type); 73 74 WARN_ON(!type_is_int(type)); 75 76 return bits <= inline_bits; 77 } 78 79 static s_max get_signed_val(struct type_descriptor *type, void *val) 80 { 81 if (is_inline_int(type)) { 82 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type); 83 unsigned long ulong_val = (unsigned long)val; 84 85 return ((s_max)ulong_val) << extra_bits >> extra_bits; 86 } 87 88 if (type_bit_width(type) == 64) 89 return *(s64 *)val; 90 91 return *(s_max *)val; 92 } 93 94 static bool val_is_negative(struct type_descriptor *type, void *val) 95 { 96 return type_is_signed(type) && get_signed_val(type, val) < 0; 97 } 98 99 static u_max get_unsigned_val(struct type_descriptor *type, void *val) 100 { 101 if (is_inline_int(type)) 102 return (unsigned long)val; 103 104 if (type_bit_width(type) == 64) 105 return *(u64 *)val; 106 107 return *(u_max *)val; 108 } 109 110 static void val_to_string(char *str, size_t size, struct type_descriptor *type, 111 void *value) 112 { 113 if (type_is_int(type)) { 114 if (type_bit_width(type) == 128) { 115 #if defined(CONFIG_ARCH_SUPPORTS_INT128) 116 u_max val = get_unsigned_val(type, value); 117 118 scnprintf(str, size, "0x%08x%08x%08x%08x", 119 (u32)(val >> 96), 120 (u32)(val >> 64), 121 (u32)(val >> 32), 122 (u32)(val)); 123 #else 124 WARN_ON(1); 125 #endif 126 } else if (type_is_signed(type)) { 127 scnprintf(str, size, "%lld", 128 (s64)get_signed_val(type, value)); 129 } else { 130 scnprintf(str, size, "%llu", 131 (u64)get_unsigned_val(type, value)); 132 } 133 } 134 } 135 136 static void ubsan_prologue(struct source_location *loc, const char *reason) 137 { 138 current->in_ubsan++; 139 140 pr_err("========================================" 141 "========================================\n"); 142 pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name, 143 loc->line & LINE_MASK, loc->column & COLUMN_MASK); 144 } 145 146 static void ubsan_epilogue(void) 147 { 148 dump_stack(); 149 pr_err("========================================" 150 "========================================\n"); 151 152 current->in_ubsan--; 153 154 if (panic_on_warn) { 155 /* 156 * This thread may hit another WARN() in the panic path. 157 * Resetting this prevents additional WARN() from panicking the 158 * system on this thread. Other threads are blocked by the 159 * panic_mutex in panic(). 160 */ 161 panic_on_warn = 0; 162 panic("panic_on_warn set ...\n"); 163 } 164 } 165 166 static void handle_overflow(struct overflow_data *data, void *lhs, 167 void *rhs, char op) 168 { 169 170 struct type_descriptor *type = data->type; 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, type_is_signed(type) ? 178 "signed-integer-overflow" : 179 "unsigned-integer-overflow"); 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 %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(); 190 } 191 192 void __ubsan_handle_add_overflow(void *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(void *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(void *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(void *_data, void *old_val) 215 { 216 struct overflow_data *data = _data; 217 char old_val_str[VALUE_LENGTH]; 218 219 if (suppress_report(&data->location)) 220 return; 221 222 ubsan_prologue(&data->location, "negation-overflow"); 223 224 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); 225 226 pr_err("negation of %s cannot be represented in type %s:\n", 227 old_val_str, data->type->type_name); 228 229 ubsan_epilogue(); 230 } 231 EXPORT_SYMBOL(__ubsan_handle_negate_overflow); 232 233 234 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) 235 { 236 struct overflow_data *data = _data; 237 char rhs_val_str[VALUE_LENGTH]; 238 239 if (suppress_report(&data->location)) 240 return; 241 242 ubsan_prologue(&data->location, "division-overflow"); 243 244 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 245 246 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 247 pr_err("division of %s by -1 cannot be represented in type %s\n", 248 rhs_val_str, data->type->type_name); 249 else 250 pr_err("division by zero\n"); 251 252 ubsan_epilogue(); 253 } 254 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 255 256 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 257 { 258 if (suppress_report(data->location)) 259 return; 260 261 ubsan_prologue(data->location, "null-ptr-deref"); 262 263 pr_err("%s null pointer of type %s\n", 264 type_check_kinds[data->type_check_kind], 265 data->type->type_name); 266 267 ubsan_epilogue(); 268 } 269 270 static void handle_misaligned_access(struct type_mismatch_data_common *data, 271 unsigned long ptr) 272 { 273 if (suppress_report(data->location)) 274 return; 275 276 ubsan_prologue(data->location, "misaligned-access"); 277 278 pr_err("%s misaligned address %p for type %s\n", 279 type_check_kinds[data->type_check_kind], 280 (void *)ptr, data->type->type_name); 281 pr_err("which requires %ld byte alignment\n", data->alignment); 282 283 ubsan_epilogue(); 284 } 285 286 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 287 unsigned long ptr) 288 { 289 if (suppress_report(data->location)) 290 return; 291 292 ubsan_prologue(data->location, "object-size-mismatch"); 293 pr_err("%s address %p with insufficient space\n", 294 type_check_kinds[data->type_check_kind], 295 (void *) ptr); 296 pr_err("for an object of type %s\n", data->type->type_name); 297 ubsan_epilogue(); 298 } 299 300 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 301 unsigned long ptr) 302 { 303 unsigned long flags = user_access_save(); 304 305 if (!ptr) 306 handle_null_ptr_deref(data); 307 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 308 handle_misaligned_access(data, ptr); 309 else 310 handle_object_size_mismatch(data, ptr); 311 312 user_access_restore(flags); 313 } 314 315 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 316 void *ptr) 317 { 318 struct type_mismatch_data_common common_data = { 319 .location = &data->location, 320 .type = data->type, 321 .alignment = data->alignment, 322 .type_check_kind = data->type_check_kind 323 }; 324 325 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 326 } 327 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 328 329 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr) 330 { 331 struct type_mismatch_data_v1 *data = _data; 332 struct type_mismatch_data_common common_data = { 333 .location = &data->location, 334 .type = data->type, 335 .alignment = 1UL << data->log_alignment, 336 .type_check_kind = data->type_check_kind 337 }; 338 339 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 340 } 341 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 342 343 void __ubsan_handle_out_of_bounds(void *_data, void *index) 344 { 345 struct out_of_bounds_data *data = _data; 346 char index_str[VALUE_LENGTH]; 347 348 if (suppress_report(&data->location)) 349 return; 350 351 ubsan_prologue(&data->location, "array-index-out-of-bounds"); 352 353 val_to_string(index_str, sizeof(index_str), data->index_type, index); 354 pr_err("index %s is out of range for type %s\n", index_str, 355 data->array_type->type_name); 356 ubsan_epilogue(); 357 } 358 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 359 360 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs) 361 { 362 struct shift_out_of_bounds_data *data = _data; 363 struct type_descriptor *rhs_type = data->rhs_type; 364 struct type_descriptor *lhs_type = data->lhs_type; 365 char rhs_str[VALUE_LENGTH]; 366 char lhs_str[VALUE_LENGTH]; 367 unsigned long ua_flags = user_access_save(); 368 369 if (suppress_report(&data->location)) 370 goto out; 371 372 ubsan_prologue(&data->location, "shift-out-of-bounds"); 373 374 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 375 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 376 377 if (val_is_negative(rhs_type, rhs)) 378 pr_err("shift exponent %s is negative\n", rhs_str); 379 380 else if (get_unsigned_val(rhs_type, rhs) >= 381 type_bit_width(lhs_type)) 382 pr_err("shift exponent %s is too large for %u-bit type %s\n", 383 rhs_str, 384 type_bit_width(lhs_type), 385 lhs_type->type_name); 386 else if (val_is_negative(lhs_type, lhs)) 387 pr_err("left shift of negative value %s\n", 388 lhs_str); 389 else 390 pr_err("left shift of %s by %s places cannot be" 391 " represented in type %s\n", 392 lhs_str, rhs_str, 393 lhs_type->type_name); 394 395 ubsan_epilogue(); 396 out: 397 user_access_restore(ua_flags); 398 } 399 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 400 401 402 void __ubsan_handle_builtin_unreachable(void *_data) 403 { 404 struct unreachable_data *data = _data; 405 ubsan_prologue(&data->location, "unreachable"); 406 pr_err("calling __builtin_unreachable()\n"); 407 ubsan_epilogue(); 408 panic("can't return from __builtin_unreachable()"); 409 } 410 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 411 412 void __ubsan_handle_load_invalid_value(void *_data, void *val) 413 { 414 struct invalid_value_data *data = _data; 415 char val_str[VALUE_LENGTH]; 416 417 if (suppress_report(&data->location)) 418 return; 419 420 ubsan_prologue(&data->location, "invalid-load"); 421 422 val_to_string(val_str, sizeof(val_str), data->type, val); 423 424 pr_err("load of value %s is not a valid value for type %s\n", 425 val_str, data->type->type_name); 426 427 ubsan_epilogue(); 428 } 429 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 430