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 check_panic_on_warn("UBSAN"); 158 } 159 160 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) 161 { 162 struct overflow_data *data = _data; 163 char rhs_val_str[VALUE_LENGTH]; 164 165 if (suppress_report(&data->location)) 166 return; 167 168 ubsan_prologue(&data->location, "division-overflow"); 169 170 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 171 172 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 173 pr_err("division of %s by -1 cannot be represented in type %s\n", 174 rhs_val_str, data->type->type_name); 175 else 176 pr_err("division by zero\n"); 177 178 ubsan_epilogue(); 179 } 180 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 181 182 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 183 { 184 if (suppress_report(data->location)) 185 return; 186 187 ubsan_prologue(data->location, "null-ptr-deref"); 188 189 pr_err("%s null pointer of type %s\n", 190 type_check_kinds[data->type_check_kind], 191 data->type->type_name); 192 193 ubsan_epilogue(); 194 } 195 196 static void handle_misaligned_access(struct type_mismatch_data_common *data, 197 unsigned long ptr) 198 { 199 if (suppress_report(data->location)) 200 return; 201 202 ubsan_prologue(data->location, "misaligned-access"); 203 204 pr_err("%s misaligned address %p for type %s\n", 205 type_check_kinds[data->type_check_kind], 206 (void *)ptr, data->type->type_name); 207 pr_err("which requires %ld byte alignment\n", data->alignment); 208 209 ubsan_epilogue(); 210 } 211 212 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 213 unsigned long ptr) 214 { 215 if (suppress_report(data->location)) 216 return; 217 218 ubsan_prologue(data->location, "object-size-mismatch"); 219 pr_err("%s address %p with insufficient space\n", 220 type_check_kinds[data->type_check_kind], 221 (void *) ptr); 222 pr_err("for an object of type %s\n", data->type->type_name); 223 ubsan_epilogue(); 224 } 225 226 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 227 unsigned long ptr) 228 { 229 unsigned long flags = user_access_save(); 230 231 if (!ptr) 232 handle_null_ptr_deref(data); 233 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 234 handle_misaligned_access(data, ptr); 235 else 236 handle_object_size_mismatch(data, ptr); 237 238 user_access_restore(flags); 239 } 240 241 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 242 void *ptr) 243 { 244 struct type_mismatch_data_common common_data = { 245 .location = &data->location, 246 .type = data->type, 247 .alignment = data->alignment, 248 .type_check_kind = data->type_check_kind 249 }; 250 251 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 252 } 253 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 254 255 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr) 256 { 257 struct type_mismatch_data_v1 *data = _data; 258 struct type_mismatch_data_common common_data = { 259 .location = &data->location, 260 .type = data->type, 261 .alignment = 1UL << data->log_alignment, 262 .type_check_kind = data->type_check_kind 263 }; 264 265 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 266 } 267 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 268 269 void __ubsan_handle_out_of_bounds(void *_data, void *index) 270 { 271 struct out_of_bounds_data *data = _data; 272 char index_str[VALUE_LENGTH]; 273 274 if (suppress_report(&data->location)) 275 return; 276 277 ubsan_prologue(&data->location, "array-index-out-of-bounds"); 278 279 val_to_string(index_str, sizeof(index_str), data->index_type, index); 280 pr_err("index %s is out of range for type %s\n", index_str, 281 data->array_type->type_name); 282 ubsan_epilogue(); 283 } 284 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 285 286 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs) 287 { 288 struct shift_out_of_bounds_data *data = _data; 289 struct type_descriptor *rhs_type = data->rhs_type; 290 struct type_descriptor *lhs_type = data->lhs_type; 291 char rhs_str[VALUE_LENGTH]; 292 char lhs_str[VALUE_LENGTH]; 293 unsigned long ua_flags = user_access_save(); 294 295 if (suppress_report(&data->location)) 296 goto out; 297 298 ubsan_prologue(&data->location, "shift-out-of-bounds"); 299 300 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 301 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 302 303 if (val_is_negative(rhs_type, rhs)) 304 pr_err("shift exponent %s is negative\n", rhs_str); 305 306 else if (get_unsigned_val(rhs_type, rhs) >= 307 type_bit_width(lhs_type)) 308 pr_err("shift exponent %s is too large for %u-bit type %s\n", 309 rhs_str, 310 type_bit_width(lhs_type), 311 lhs_type->type_name); 312 else if (val_is_negative(lhs_type, lhs)) 313 pr_err("left shift of negative value %s\n", 314 lhs_str); 315 else 316 pr_err("left shift of %s by %s places cannot be" 317 " represented in type %s\n", 318 lhs_str, rhs_str, 319 lhs_type->type_name); 320 321 ubsan_epilogue(); 322 out: 323 user_access_restore(ua_flags); 324 } 325 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 326 327 328 void __ubsan_handle_builtin_unreachable(void *_data) 329 { 330 struct unreachable_data *data = _data; 331 ubsan_prologue(&data->location, "unreachable"); 332 pr_err("calling __builtin_unreachable()\n"); 333 ubsan_epilogue(); 334 panic("can't return from __builtin_unreachable()"); 335 } 336 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 337 338 void __ubsan_handle_load_invalid_value(void *_data, void *val) 339 { 340 struct invalid_value_data *data = _data; 341 char val_str[VALUE_LENGTH]; 342 343 if (suppress_report(&data->location)) 344 return; 345 346 ubsan_prologue(&data->location, "invalid-load"); 347 348 val_to_string(val_str, sizeof(val_str), data->type, val); 349 350 pr_err("load of value %s is not a valid value for type %s\n", 351 val_str, data->type->type_name); 352 353 ubsan_epilogue(); 354 } 355 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 356 357 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 358 unsigned long align, 359 unsigned long offset); 360 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 361 unsigned long align, 362 unsigned long offset) 363 { 364 struct alignment_assumption_data *data = _data; 365 unsigned long real_ptr; 366 367 if (suppress_report(&data->location)) 368 return; 369 370 ubsan_prologue(&data->location, "alignment-assumption"); 371 372 if (offset) 373 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed", 374 align, offset, data->type->type_name); 375 else 376 pr_err("assumption of %lu byte alignment for pointer of type %s failed", 377 align, data->type->type_name); 378 379 real_ptr = ptr - offset; 380 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes", 381 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0), 382 real_ptr & (align - 1)); 383 384 ubsan_epilogue(); 385 } 386 EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); 387