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 20const 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 43static bool was_reported(struct source_location *location) 44{ 45 return test_and_set_bit(REPORTED_BIT, &location->reported); 46} 47 48static bool suppress_report(struct source_location *loc) 49{ 50 return current->in_ubsan || was_reported(loc); 51} 52 53static bool type_is_int(struct type_descriptor *type) 54{ 55 return type->type_kind == type_kind_int; 56} 57 58static bool type_is_signed(struct type_descriptor *type) 59{ 60 WARN_ON(!type_is_int(type)); 61 return type->type_info & 1; 62} 63 64static unsigned type_bit_width(struct type_descriptor *type) 65{ 66 return 1 << (type->type_info >> 1); 67} 68 69static 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 79static 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 94static 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 99static 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 110static 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 136static 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 146static void ubsan_epilogue(void) 147{ 148 dump_stack(); 149 pr_err("========================================" 150 "========================================\n"); 151 152 current->in_ubsan--; 153 154 check_panic_on_warn("UBSAN"); 155} 156 157static void handle_overflow(struct overflow_data *data, void *lhs, 158 void *rhs, char op) 159{ 160 161 struct type_descriptor *type = data->type; 162 char lhs_val_str[VALUE_LENGTH]; 163 char rhs_val_str[VALUE_LENGTH]; 164 165 if (suppress_report(&data->location)) 166 return; 167 168 ubsan_prologue(&data->location, type_is_signed(type) ? 169 "signed-integer-overflow" : 170 "unsigned-integer-overflow"); 171 172 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); 173 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); 174 pr_err("%s %c %s cannot be represented in type %s\n", 175 lhs_val_str, 176 op, 177 rhs_val_str, 178 type->type_name); 179 180 ubsan_epilogue(); 181} 182 183void __ubsan_handle_add_overflow(void *data, 184 void *lhs, void *rhs) 185{ 186 187 handle_overflow(data, lhs, rhs, '+'); 188} 189EXPORT_SYMBOL(__ubsan_handle_add_overflow); 190 191void __ubsan_handle_sub_overflow(void *data, 192 void *lhs, void *rhs) 193{ 194 handle_overflow(data, lhs, rhs, '-'); 195} 196EXPORT_SYMBOL(__ubsan_handle_sub_overflow); 197 198void __ubsan_handle_mul_overflow(void *data, 199 void *lhs, void *rhs) 200{ 201 handle_overflow(data, lhs, rhs, '*'); 202} 203EXPORT_SYMBOL(__ubsan_handle_mul_overflow); 204 205void __ubsan_handle_negate_overflow(void *_data, void *old_val) 206{ 207 struct overflow_data *data = _data; 208 char old_val_str[VALUE_LENGTH]; 209 210 if (suppress_report(&data->location)) 211 return; 212 213 ubsan_prologue(&data->location, "negation-overflow"); 214 215 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); 216 217 pr_err("negation of %s cannot be represented in type %s:\n", 218 old_val_str, data->type->type_name); 219 220 ubsan_epilogue(); 221} 222EXPORT_SYMBOL(__ubsan_handle_negate_overflow); 223 224 225void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) 226{ 227 struct overflow_data *data = _data; 228 char rhs_val_str[VALUE_LENGTH]; 229 230 if (suppress_report(&data->location)) 231 return; 232 233 ubsan_prologue(&data->location, "division-overflow"); 234 235 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 236 237 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 238 pr_err("division of %s by -1 cannot be represented in type %s\n", 239 rhs_val_str, data->type->type_name); 240 else 241 pr_err("division by zero\n"); 242 243 ubsan_epilogue(); 244} 245EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 246 247static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 248{ 249 if (suppress_report(data->location)) 250 return; 251 252 ubsan_prologue(data->location, "null-ptr-deref"); 253 254 pr_err("%s null pointer of type %s\n", 255 type_check_kinds[data->type_check_kind], 256 data->type->type_name); 257 258 ubsan_epilogue(); 259} 260 261static void handle_misaligned_access(struct type_mismatch_data_common *data, 262 unsigned long ptr) 263{ 264 if (suppress_report(data->location)) 265 return; 266 267 ubsan_prologue(data->location, "misaligned-access"); 268 269 pr_err("%s misaligned address %p for type %s\n", 270 type_check_kinds[data->type_check_kind], 271 (void *)ptr, data->type->type_name); 272 pr_err("which requires %ld byte alignment\n", data->alignment); 273 274 ubsan_epilogue(); 275} 276 277static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 278 unsigned long ptr) 279{ 280 if (suppress_report(data->location)) 281 return; 282 283 ubsan_prologue(data->location, "object-size-mismatch"); 284 pr_err("%s address %p with insufficient space\n", 285 type_check_kinds[data->type_check_kind], 286 (void *) ptr); 287 pr_err("for an object of type %s\n", data->type->type_name); 288 ubsan_epilogue(); 289} 290 291static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 292 unsigned long ptr) 293{ 294 unsigned long flags = user_access_save(); 295 296 if (!ptr) 297 handle_null_ptr_deref(data); 298 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 299 handle_misaligned_access(data, ptr); 300 else 301 handle_object_size_mismatch(data, ptr); 302 303 user_access_restore(flags); 304} 305 306void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 307 void *ptr) 308{ 309 struct type_mismatch_data_common common_data = { 310 .location = &data->location, 311 .type = data->type, 312 .alignment = data->alignment, 313 .type_check_kind = data->type_check_kind 314 }; 315 316 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 317} 318EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 319 320void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr) 321{ 322 struct type_mismatch_data_v1 *data = _data; 323 struct type_mismatch_data_common common_data = { 324 .location = &data->location, 325 .type = data->type, 326 .alignment = 1UL << data->log_alignment, 327 .type_check_kind = data->type_check_kind 328 }; 329 330 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 331} 332EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 333 334void __ubsan_handle_out_of_bounds(void *_data, void *index) 335{ 336 struct out_of_bounds_data *data = _data; 337 char index_str[VALUE_LENGTH]; 338 339 if (suppress_report(&data->location)) 340 return; 341 342 ubsan_prologue(&data->location, "array-index-out-of-bounds"); 343 344 val_to_string(index_str, sizeof(index_str), data->index_type, index); 345 pr_err("index %s is out of range for type %s\n", index_str, 346 data->array_type->type_name); 347 ubsan_epilogue(); 348} 349EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 350 351void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs) 352{ 353 struct shift_out_of_bounds_data *data = _data; 354 struct type_descriptor *rhs_type = data->rhs_type; 355 struct type_descriptor *lhs_type = data->lhs_type; 356 char rhs_str[VALUE_LENGTH]; 357 char lhs_str[VALUE_LENGTH]; 358 unsigned long ua_flags = user_access_save(); 359 360 if (suppress_report(&data->location)) 361 goto out; 362 363 ubsan_prologue(&data->location, "shift-out-of-bounds"); 364 365 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 366 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 367 368 if (val_is_negative(rhs_type, rhs)) 369 pr_err("shift exponent %s is negative\n", rhs_str); 370 371 else if (get_unsigned_val(rhs_type, rhs) >= 372 type_bit_width(lhs_type)) 373 pr_err("shift exponent %s is too large for %u-bit type %s\n", 374 rhs_str, 375 type_bit_width(lhs_type), 376 lhs_type->type_name); 377 else if (val_is_negative(lhs_type, lhs)) 378 pr_err("left shift of negative value %s\n", 379 lhs_str); 380 else 381 pr_err("left shift of %s by %s places cannot be" 382 " represented in type %s\n", 383 lhs_str, rhs_str, 384 lhs_type->type_name); 385 386 ubsan_epilogue(); 387out: 388 user_access_restore(ua_flags); 389} 390EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 391 392 393void __ubsan_handle_builtin_unreachable(void *_data) 394{ 395 struct unreachable_data *data = _data; 396 ubsan_prologue(&data->location, "unreachable"); 397 pr_err("calling __builtin_unreachable()\n"); 398 ubsan_epilogue(); 399 panic("can't return from __builtin_unreachable()"); 400} 401EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 402 403void __ubsan_handle_load_invalid_value(void *_data, void *val) 404{ 405 struct invalid_value_data *data = _data; 406 char val_str[VALUE_LENGTH]; 407 408 if (suppress_report(&data->location)) 409 return; 410 411 ubsan_prologue(&data->location, "invalid-load"); 412 413 val_to_string(val_str, sizeof(val_str), data->type, val); 414 415 pr_err("load of value %s is not a valid value for type %s\n", 416 val_str, data->type->type_name); 417 418 ubsan_epilogue(); 419} 420EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 421 422void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 423 unsigned long align, 424 unsigned long offset); 425void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 426 unsigned long align, 427 unsigned long offset) 428{ 429 struct alignment_assumption_data *data = _data; 430 unsigned long real_ptr; 431 432 if (suppress_report(&data->location)) 433 return; 434 435 ubsan_prologue(&data->location, "alignment-assumption"); 436 437 if (offset) 438 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed", 439 align, offset, data->type->type_name); 440 else 441 pr_err("assumption of %lu byte alignment for pointer of type %s failed", 442 align, data->type->type_name); 443 444 real_ptr = ptr - offset; 445 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes", 446 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0), 447 real_ptr & (align - 1)); 448 449 ubsan_epilogue(); 450} 451EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); 452