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 #include <linux/ubsan.h> 18 #include <kunit/test-bug.h> 19 20 #include "ubsan.h" 21 22 #ifdef CONFIG_UBSAN_TRAP 23 /* 24 * Only include matches for UBSAN checks that are actually compiled in. 25 * The mappings of struct SanitizerKind (the -fsanitize=xxx args) to 26 * enum SanitizerHandler (the traps) in Clang is in clang/lib/CodeGen/. 27 */ 28 const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type) 29 { 30 switch (check_type) { 31 #ifdef CONFIG_UBSAN_BOUNDS 32 /* 33 * SanitizerKind::ArrayBounds and SanitizerKind::LocalBounds 34 * emit SanitizerHandler::OutOfBounds. 35 */ 36 case ubsan_out_of_bounds: 37 return "UBSAN: array index out of bounds"; 38 #endif 39 #ifdef CONFIG_UBSAN_SHIFT 40 /* 41 * SanitizerKind::ShiftBase and SanitizerKind::ShiftExponent 42 * emit SanitizerHandler::ShiftOutOfBounds. 43 */ 44 case ubsan_shift_out_of_bounds: 45 return "UBSAN: shift out of bounds"; 46 #endif 47 #ifdef CONFIG_UBSAN_DIV_ZERO 48 /* 49 * SanitizerKind::IntegerDivideByZero emits 50 * SanitizerHandler::DivremOverflow. 51 */ 52 case ubsan_divrem_overflow: 53 return "UBSAN: divide/remainder overflow"; 54 #endif 55 #ifdef CONFIG_UBSAN_UNREACHABLE 56 /* 57 * SanitizerKind::Unreachable emits 58 * SanitizerHandler::BuiltinUnreachable. 59 */ 60 case ubsan_builtin_unreachable: 61 return "UBSAN: unreachable code"; 62 #endif 63 #if defined(CONFIG_UBSAN_BOOL) || defined(CONFIG_UBSAN_ENUM) 64 /* 65 * SanitizerKind::Bool and SanitizerKind::Enum emit 66 * SanitizerHandler::LoadInvalidValue. 67 */ 68 case ubsan_load_invalid_value: 69 return "UBSAN: loading invalid value"; 70 #endif 71 #ifdef CONFIG_UBSAN_ALIGNMENT 72 /* 73 * SanitizerKind::Alignment emits SanitizerHandler::TypeMismatch 74 * or SanitizerHandler::AlignmentAssumption. 75 */ 76 case ubsan_alignment_assumption: 77 return "UBSAN: alignment assumption"; 78 case ubsan_type_mismatch: 79 return "UBSAN: type mismatch"; 80 #endif 81 default: 82 return "UBSAN: unrecognized failure code"; 83 } 84 } 85 86 #else 87 static const char * const type_check_kinds[] = { 88 "load of", 89 "store to", 90 "reference binding to", 91 "member access within", 92 "member call on", 93 "constructor call on", 94 "downcast of", 95 "downcast of" 96 }; 97 98 #define REPORTED_BIT 31 99 100 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN) 101 #define COLUMN_MASK (~(1U << REPORTED_BIT)) 102 #define LINE_MASK (~0U) 103 #else 104 #define COLUMN_MASK (~0U) 105 #define LINE_MASK (~(1U << REPORTED_BIT)) 106 #endif 107 108 #define VALUE_LENGTH 40 109 110 static bool was_reported(struct source_location *location) 111 { 112 return test_and_set_bit(REPORTED_BIT, &location->reported); 113 } 114 115 static bool suppress_report(struct source_location *loc) 116 { 117 return current->in_ubsan || was_reported(loc); 118 } 119 120 static bool type_is_int(struct type_descriptor *type) 121 { 122 return type->type_kind == type_kind_int; 123 } 124 125 static bool type_is_signed(struct type_descriptor *type) 126 { 127 WARN_ON(!type_is_int(type)); 128 return type->type_info & 1; 129 } 130 131 static unsigned type_bit_width(struct type_descriptor *type) 132 { 133 return 1 << (type->type_info >> 1); 134 } 135 136 static bool is_inline_int(struct type_descriptor *type) 137 { 138 unsigned inline_bits = sizeof(unsigned long)*8; 139 unsigned bits = type_bit_width(type); 140 141 WARN_ON(!type_is_int(type)); 142 143 return bits <= inline_bits; 144 } 145 146 static s_max get_signed_val(struct type_descriptor *type, void *val) 147 { 148 if (is_inline_int(type)) { 149 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type); 150 unsigned long ulong_val = (unsigned long)val; 151 152 return ((s_max)ulong_val) << extra_bits >> extra_bits; 153 } 154 155 if (type_bit_width(type) == 64) 156 return *(s64 *)val; 157 158 return *(s_max *)val; 159 } 160 161 static bool val_is_negative(struct type_descriptor *type, void *val) 162 { 163 return type_is_signed(type) && get_signed_val(type, val) < 0; 164 } 165 166 static u_max get_unsigned_val(struct type_descriptor *type, void *val) 167 { 168 if (is_inline_int(type)) 169 return (unsigned long)val; 170 171 if (type_bit_width(type) == 64) 172 return *(u64 *)val; 173 174 return *(u_max *)val; 175 } 176 177 static void val_to_string(char *str, size_t size, struct type_descriptor *type, 178 void *value) 179 { 180 if (type_is_int(type)) { 181 if (type_bit_width(type) == 128) { 182 #if defined(CONFIG_ARCH_SUPPORTS_INT128) 183 u_max val = get_unsigned_val(type, value); 184 185 scnprintf(str, size, "0x%08x%08x%08x%08x", 186 (u32)(val >> 96), 187 (u32)(val >> 64), 188 (u32)(val >> 32), 189 (u32)(val)); 190 #else 191 WARN_ON(1); 192 #endif 193 } else if (type_is_signed(type)) { 194 scnprintf(str, size, "%lld", 195 (s64)get_signed_val(type, value)); 196 } else { 197 scnprintf(str, size, "%llu", 198 (u64)get_unsigned_val(type, value)); 199 } 200 } 201 } 202 203 static void ubsan_prologue(struct source_location *loc, const char *reason) 204 { 205 current->in_ubsan++; 206 207 pr_err("========================================" 208 "========================================\n"); 209 pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name, 210 loc->line & LINE_MASK, loc->column & COLUMN_MASK); 211 212 kunit_fail_current_test("%s in %s", reason, loc->file_name); 213 } 214 215 static void ubsan_epilogue(void) 216 { 217 dump_stack(); 218 pr_err("========================================" 219 "========================================\n"); 220 221 current->in_ubsan--; 222 223 check_panic_on_warn("UBSAN"); 224 } 225 226 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) 227 { 228 struct overflow_data *data = _data; 229 char rhs_val_str[VALUE_LENGTH]; 230 231 if (suppress_report(&data->location)) 232 return; 233 234 ubsan_prologue(&data->location, "division-overflow"); 235 236 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 237 238 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 239 pr_err("division of %s by -1 cannot be represented in type %s\n", 240 rhs_val_str, data->type->type_name); 241 else 242 pr_err("division by zero\n"); 243 244 ubsan_epilogue(); 245 } 246 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 247 248 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 249 { 250 if (suppress_report(data->location)) 251 return; 252 253 ubsan_prologue(data->location, "null-ptr-deref"); 254 255 pr_err("%s null pointer of type %s\n", 256 type_check_kinds[data->type_check_kind], 257 data->type->type_name); 258 259 ubsan_epilogue(); 260 } 261 262 static void handle_misaligned_access(struct type_mismatch_data_common *data, 263 unsigned long ptr) 264 { 265 if (suppress_report(data->location)) 266 return; 267 268 ubsan_prologue(data->location, "misaligned-access"); 269 270 pr_err("%s misaligned address %p for type %s\n", 271 type_check_kinds[data->type_check_kind], 272 (void *)ptr, data->type->type_name); 273 pr_err("which requires %ld byte alignment\n", data->alignment); 274 275 ubsan_epilogue(); 276 } 277 278 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 279 unsigned long ptr) 280 { 281 if (suppress_report(data->location)) 282 return; 283 284 ubsan_prologue(data->location, "object-size-mismatch"); 285 pr_err("%s address %p with insufficient space\n", 286 type_check_kinds[data->type_check_kind], 287 (void *) ptr); 288 pr_err("for an object of type %s\n", data->type->type_name); 289 ubsan_epilogue(); 290 } 291 292 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 293 unsigned long ptr) 294 { 295 unsigned long flags = user_access_save(); 296 297 if (!ptr) 298 handle_null_ptr_deref(data); 299 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 300 handle_misaligned_access(data, ptr); 301 else 302 handle_object_size_mismatch(data, ptr); 303 304 user_access_restore(flags); 305 } 306 307 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 308 void *ptr) 309 { 310 struct type_mismatch_data_common common_data = { 311 .location = &data->location, 312 .type = data->type, 313 .alignment = data->alignment, 314 .type_check_kind = data->type_check_kind 315 }; 316 317 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 318 } 319 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 320 321 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr) 322 { 323 struct type_mismatch_data_v1 *data = _data; 324 struct type_mismatch_data_common common_data = { 325 .location = &data->location, 326 .type = data->type, 327 .alignment = 1UL << data->log_alignment, 328 .type_check_kind = data->type_check_kind 329 }; 330 331 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 332 } 333 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 334 335 void __ubsan_handle_out_of_bounds(void *_data, void *index) 336 { 337 struct out_of_bounds_data *data = _data; 338 char index_str[VALUE_LENGTH]; 339 340 if (suppress_report(&data->location)) 341 return; 342 343 ubsan_prologue(&data->location, "array-index-out-of-bounds"); 344 345 val_to_string(index_str, sizeof(index_str), data->index_type, index); 346 pr_err("index %s is out of range for type %s\n", index_str, 347 data->array_type->type_name); 348 ubsan_epilogue(); 349 } 350 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 351 352 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs) 353 { 354 struct shift_out_of_bounds_data *data = _data; 355 struct type_descriptor *rhs_type = data->rhs_type; 356 struct type_descriptor *lhs_type = data->lhs_type; 357 char rhs_str[VALUE_LENGTH]; 358 char lhs_str[VALUE_LENGTH]; 359 unsigned long ua_flags = user_access_save(); 360 361 if (suppress_report(&data->location)) 362 goto out; 363 364 ubsan_prologue(&data->location, "shift-out-of-bounds"); 365 366 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 367 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 368 369 if (val_is_negative(rhs_type, rhs)) 370 pr_err("shift exponent %s is negative\n", rhs_str); 371 372 else if (get_unsigned_val(rhs_type, rhs) >= 373 type_bit_width(lhs_type)) 374 pr_err("shift exponent %s is too large for %u-bit type %s\n", 375 rhs_str, 376 type_bit_width(lhs_type), 377 lhs_type->type_name); 378 else if (val_is_negative(lhs_type, lhs)) 379 pr_err("left shift of negative value %s\n", 380 lhs_str); 381 else 382 pr_err("left shift of %s by %s places cannot be" 383 " represented in type %s\n", 384 lhs_str, rhs_str, 385 lhs_type->type_name); 386 387 ubsan_epilogue(); 388 out: 389 user_access_restore(ua_flags); 390 } 391 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 392 393 394 void __ubsan_handle_builtin_unreachable(void *_data) 395 { 396 struct unreachable_data *data = _data; 397 ubsan_prologue(&data->location, "unreachable"); 398 pr_err("calling __builtin_unreachable()\n"); 399 ubsan_epilogue(); 400 panic("can't return from __builtin_unreachable()"); 401 } 402 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 403 404 void __ubsan_handle_load_invalid_value(void *_data, void *val) 405 { 406 struct invalid_value_data *data = _data; 407 char val_str[VALUE_LENGTH]; 408 unsigned long ua_flags = user_access_save(); 409 410 if (suppress_report(&data->location)) 411 goto out; 412 413 ubsan_prologue(&data->location, "invalid-load"); 414 415 val_to_string(val_str, sizeof(val_str), data->type, val); 416 417 pr_err("load of value %s is not a valid value for type %s\n", 418 val_str, data->type->type_name); 419 420 ubsan_epilogue(); 421 out: 422 user_access_restore(ua_flags); 423 } 424 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 425 426 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 427 unsigned long align, 428 unsigned long offset) 429 { 430 struct alignment_assumption_data *data = _data; 431 unsigned long real_ptr; 432 433 if (suppress_report(&data->location)) 434 return; 435 436 ubsan_prologue(&data->location, "alignment-assumption"); 437 438 if (offset) 439 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed", 440 align, offset, data->type->type_name); 441 else 442 pr_err("assumption of %lu byte alignment for pointer of type %s failed", 443 align, data->type->type_name); 444 445 real_ptr = ptr - offset; 446 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes", 447 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0), 448 real_ptr & (align - 1)); 449 450 ubsan_epilogue(); 451 } 452 EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); 453 454 #endif /* !CONFIG_UBSAN_TRAP */ 455