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