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 panic("panic_on_warn set ...\n"); 159 } 160 161 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) 162 { 163 struct overflow_data *data = _data; 164 char rhs_val_str[VALUE_LENGTH]; 165 166 if (suppress_report(&data->location)) 167 return; 168 169 ubsan_prologue(&data->location, "division-overflow"); 170 171 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 172 173 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 174 pr_err("division of %s by -1 cannot be represented in type %s\n", 175 rhs_val_str, data->type->type_name); 176 else 177 pr_err("division by zero\n"); 178 179 ubsan_epilogue(); 180 } 181 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 182 183 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 184 { 185 if (suppress_report(data->location)) 186 return; 187 188 ubsan_prologue(data->location, "null-ptr-deref"); 189 190 pr_err("%s null pointer of type %s\n", 191 type_check_kinds[data->type_check_kind], 192 data->type->type_name); 193 194 ubsan_epilogue(); 195 } 196 197 static void handle_misaligned_access(struct type_mismatch_data_common *data, 198 unsigned long ptr) 199 { 200 if (suppress_report(data->location)) 201 return; 202 203 ubsan_prologue(data->location, "misaligned-access"); 204 205 pr_err("%s misaligned address %p for type %s\n", 206 type_check_kinds[data->type_check_kind], 207 (void *)ptr, data->type->type_name); 208 pr_err("which requires %ld byte alignment\n", data->alignment); 209 210 ubsan_epilogue(); 211 } 212 213 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 214 unsigned long ptr) 215 { 216 if (suppress_report(data->location)) 217 return; 218 219 ubsan_prologue(data->location, "object-size-mismatch"); 220 pr_err("%s address %p with insufficient space\n", 221 type_check_kinds[data->type_check_kind], 222 (void *) ptr); 223 pr_err("for an object of type %s\n", data->type->type_name); 224 ubsan_epilogue(); 225 } 226 227 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 228 unsigned long ptr) 229 { 230 unsigned long flags = user_access_save(); 231 232 if (!ptr) 233 handle_null_ptr_deref(data); 234 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 235 handle_misaligned_access(data, ptr); 236 else 237 handle_object_size_mismatch(data, ptr); 238 239 user_access_restore(flags); 240 } 241 242 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 243 void *ptr) 244 { 245 struct type_mismatch_data_common common_data = { 246 .location = &data->location, 247 .type = data->type, 248 .alignment = data->alignment, 249 .type_check_kind = data->type_check_kind 250 }; 251 252 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 253 } 254 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 255 256 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr) 257 { 258 struct type_mismatch_data_v1 *data = _data; 259 struct type_mismatch_data_common common_data = { 260 .location = &data->location, 261 .type = data->type, 262 .alignment = 1UL << data->log_alignment, 263 .type_check_kind = data->type_check_kind 264 }; 265 266 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 267 } 268 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 269 270 void __ubsan_handle_out_of_bounds(void *_data, void *index) 271 { 272 struct out_of_bounds_data *data = _data; 273 char index_str[VALUE_LENGTH]; 274 275 if (suppress_report(&data->location)) 276 return; 277 278 ubsan_prologue(&data->location, "array-index-out-of-bounds"); 279 280 val_to_string(index_str, sizeof(index_str), data->index_type, index); 281 pr_err("index %s is out of range for type %s\n", index_str, 282 data->array_type->type_name); 283 ubsan_epilogue(); 284 } 285 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 286 287 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs) 288 { 289 struct shift_out_of_bounds_data *data = _data; 290 struct type_descriptor *rhs_type = data->rhs_type; 291 struct type_descriptor *lhs_type = data->lhs_type; 292 char rhs_str[VALUE_LENGTH]; 293 char lhs_str[VALUE_LENGTH]; 294 unsigned long ua_flags = user_access_save(); 295 296 if (suppress_report(&data->location)) 297 goto out; 298 299 ubsan_prologue(&data->location, "shift-out-of-bounds"); 300 301 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 302 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 303 304 if (val_is_negative(rhs_type, rhs)) 305 pr_err("shift exponent %s is negative\n", rhs_str); 306 307 else if (get_unsigned_val(rhs_type, rhs) >= 308 type_bit_width(lhs_type)) 309 pr_err("shift exponent %s is too large for %u-bit type %s\n", 310 rhs_str, 311 type_bit_width(lhs_type), 312 lhs_type->type_name); 313 else if (val_is_negative(lhs_type, lhs)) 314 pr_err("left shift of negative value %s\n", 315 lhs_str); 316 else 317 pr_err("left shift of %s by %s places cannot be" 318 " represented in type %s\n", 319 lhs_str, rhs_str, 320 lhs_type->type_name); 321 322 ubsan_epilogue(); 323 out: 324 user_access_restore(ua_flags); 325 } 326 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 327 328 329 void __ubsan_handle_builtin_unreachable(void *_data) 330 { 331 struct unreachable_data *data = _data; 332 ubsan_prologue(&data->location, "unreachable"); 333 pr_err("calling __builtin_unreachable()\n"); 334 ubsan_epilogue(); 335 panic("can't return from __builtin_unreachable()"); 336 } 337 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 338 339 void __ubsan_handle_load_invalid_value(void *_data, void *val) 340 { 341 struct invalid_value_data *data = _data; 342 char val_str[VALUE_LENGTH]; 343 344 if (suppress_report(&data->location)) 345 return; 346 347 ubsan_prologue(&data->location, "invalid-load"); 348 349 val_to_string(val_str, sizeof(val_str), data->type, val); 350 351 pr_err("load of value %s is not a valid value for type %s\n", 352 val_str, data->type->type_name); 353 354 ubsan_epilogue(); 355 } 356 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 357 358 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 359 unsigned long align, 360 unsigned long offset); 361 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 362 unsigned long align, 363 unsigned long offset) 364 { 365 struct alignment_assumption_data *data = _data; 366 unsigned long real_ptr; 367 368 if (suppress_report(&data->location)) 369 return; 370 371 ubsan_prologue(&data->location, "alignment-assumption"); 372 373 if (offset) 374 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed", 375 align, offset, data->type->type_name); 376 else 377 pr_err("assumption of %lu byte alignment for pointer of type %s failed", 378 align, data->type->type_name); 379 380 real_ptr = ptr - offset; 381 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes", 382 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0), 383 real_ptr & (align - 1)); 384 385 ubsan_epilogue(); 386 } 387 EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); 388