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_warn(CUT_HERE); 208 209 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_warn("---[ end trace ]---\n"); 219 220 current->in_ubsan--; 221 222 check_panic_on_warn("UBSAN"); 223 } 224 225 void __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 } 245 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 246 247 static 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 } 260 261 static 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 } 276 277 static 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 } 290 291 static 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 } 305 306 void __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 } 318 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 319 320 void __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 } 332 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 333 334 void __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 } 349 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 350 351 void __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(); 387 out: 388 user_access_restore(ua_flags); 389 } 390 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 391 392 393 void __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 } 401 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 402 403 void __ubsan_handle_load_invalid_value(void *_data, void *val) 404 { 405 struct invalid_value_data *data = _data; 406 char val_str[VALUE_LENGTH]; 407 unsigned long ua_flags = user_access_save(); 408 409 if (suppress_report(&data->location)) 410 goto out; 411 412 ubsan_prologue(&data->location, "invalid-load"); 413 414 val_to_string(val_str, sizeof(val_str), data->type, val); 415 416 pr_err("load of value %s is not a valid value for type %s\n", 417 val_str, data->type->type_name); 418 419 ubsan_epilogue(); 420 out: 421 user_access_restore(ua_flags); 422 } 423 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 424 425 void __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 } 451 EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); 452 453 #endif /* !CONFIG_UBSAN_TRAP */ 454