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 static const char * const 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 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) 167 { 168 struct overflow_data *data = _data; 169 char rhs_val_str[VALUE_LENGTH]; 170 171 if (suppress_report(&data->location)) 172 return; 173 174 ubsan_prologue(&data->location, "division-overflow"); 175 176 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 177 178 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 179 pr_err("division of %s by -1 cannot be represented in type %s\n", 180 rhs_val_str, data->type->type_name); 181 else 182 pr_err("division by zero\n"); 183 184 ubsan_epilogue(); 185 } 186 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 187 188 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 189 { 190 if (suppress_report(data->location)) 191 return; 192 193 ubsan_prologue(data->location, "null-ptr-deref"); 194 195 pr_err("%s null pointer of type %s\n", 196 type_check_kinds[data->type_check_kind], 197 data->type->type_name); 198 199 ubsan_epilogue(); 200 } 201 202 static void handle_misaligned_access(struct type_mismatch_data_common *data, 203 unsigned long ptr) 204 { 205 if (suppress_report(data->location)) 206 return; 207 208 ubsan_prologue(data->location, "misaligned-access"); 209 210 pr_err("%s misaligned address %p for type %s\n", 211 type_check_kinds[data->type_check_kind], 212 (void *)ptr, data->type->type_name); 213 pr_err("which requires %ld byte alignment\n", data->alignment); 214 215 ubsan_epilogue(); 216 } 217 218 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 219 unsigned long ptr) 220 { 221 if (suppress_report(data->location)) 222 return; 223 224 ubsan_prologue(data->location, "object-size-mismatch"); 225 pr_err("%s address %p with insufficient space\n", 226 type_check_kinds[data->type_check_kind], 227 (void *) ptr); 228 pr_err("for an object of type %s\n", data->type->type_name); 229 ubsan_epilogue(); 230 } 231 232 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 233 unsigned long ptr) 234 { 235 unsigned long flags = user_access_save(); 236 237 if (!ptr) 238 handle_null_ptr_deref(data); 239 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 240 handle_misaligned_access(data, ptr); 241 else 242 handle_object_size_mismatch(data, ptr); 243 244 user_access_restore(flags); 245 } 246 247 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 248 void *ptr) 249 { 250 struct type_mismatch_data_common common_data = { 251 .location = &data->location, 252 .type = data->type, 253 .alignment = data->alignment, 254 .type_check_kind = data->type_check_kind 255 }; 256 257 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 258 } 259 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 260 261 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr) 262 { 263 struct type_mismatch_data_v1 *data = _data; 264 struct type_mismatch_data_common common_data = { 265 .location = &data->location, 266 .type = data->type, 267 .alignment = 1UL << data->log_alignment, 268 .type_check_kind = data->type_check_kind 269 }; 270 271 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 272 } 273 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 274 275 void __ubsan_handle_out_of_bounds(void *_data, void *index) 276 { 277 struct out_of_bounds_data *data = _data; 278 char index_str[VALUE_LENGTH]; 279 280 if (suppress_report(&data->location)) 281 return; 282 283 ubsan_prologue(&data->location, "array-index-out-of-bounds"); 284 285 val_to_string(index_str, sizeof(index_str), data->index_type, index); 286 pr_err("index %s is out of range for type %s\n", index_str, 287 data->array_type->type_name); 288 ubsan_epilogue(); 289 } 290 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 291 292 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs) 293 { 294 struct shift_out_of_bounds_data *data = _data; 295 struct type_descriptor *rhs_type = data->rhs_type; 296 struct type_descriptor *lhs_type = data->lhs_type; 297 char rhs_str[VALUE_LENGTH]; 298 char lhs_str[VALUE_LENGTH]; 299 unsigned long ua_flags = user_access_save(); 300 301 if (suppress_report(&data->location)) 302 goto out; 303 304 ubsan_prologue(&data->location, "shift-out-of-bounds"); 305 306 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 307 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 308 309 if (val_is_negative(rhs_type, rhs)) 310 pr_err("shift exponent %s is negative\n", rhs_str); 311 312 else if (get_unsigned_val(rhs_type, rhs) >= 313 type_bit_width(lhs_type)) 314 pr_err("shift exponent %s is too large for %u-bit type %s\n", 315 rhs_str, 316 type_bit_width(lhs_type), 317 lhs_type->type_name); 318 else if (val_is_negative(lhs_type, lhs)) 319 pr_err("left shift of negative value %s\n", 320 lhs_str); 321 else 322 pr_err("left shift of %s by %s places cannot be" 323 " represented in type %s\n", 324 lhs_str, rhs_str, 325 lhs_type->type_name); 326 327 ubsan_epilogue(); 328 out: 329 user_access_restore(ua_flags); 330 } 331 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 332 333 334 void __ubsan_handle_builtin_unreachable(void *_data) 335 { 336 struct unreachable_data *data = _data; 337 ubsan_prologue(&data->location, "unreachable"); 338 pr_err("calling __builtin_unreachable()\n"); 339 ubsan_epilogue(); 340 panic("can't return from __builtin_unreachable()"); 341 } 342 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 343 344 void __ubsan_handle_load_invalid_value(void *_data, void *val) 345 { 346 struct invalid_value_data *data = _data; 347 char val_str[VALUE_LENGTH]; 348 349 if (suppress_report(&data->location)) 350 return; 351 352 ubsan_prologue(&data->location, "invalid-load"); 353 354 val_to_string(val_str, sizeof(val_str), data->type, val); 355 356 pr_err("load of value %s is not a valid value for type %s\n", 357 val_str, data->type->type_name); 358 359 ubsan_epilogue(); 360 } 361 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 362 363 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 364 unsigned long align, 365 unsigned long offset); 366 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 367 unsigned long align, 368 unsigned long offset) 369 { 370 struct alignment_assumption_data *data = _data; 371 unsigned long real_ptr; 372 373 if (suppress_report(&data->location)) 374 return; 375 376 ubsan_prologue(&data->location, "alignment-assumption"); 377 378 if (offset) 379 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed", 380 align, offset, data->type->type_name); 381 else 382 pr_err("assumption of %lu byte alignment for pointer of type %s failed", 383 align, data->type->type_name); 384 385 real_ptr = ptr - offset; 386 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes", 387 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0), 388 real_ptr & (align - 1)); 389 390 ubsan_epilogue(); 391 } 392 EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); 393