lib/ubsan.c

   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 const char *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         check_panic_on_warn("UBSAN");
 155 }
 156
 157 static void handle_overflow(struct overflow_data *data, void *lhs,
 158                         void *rhs, char op)
 159 {
 160
 161         struct type_descriptor *type = data->type;
 162         char lhs_val_str[VALUE_LENGTH];
 163         char rhs_val_str[VALUE_LENGTH];
 164
 165         if (suppress_report(&data->location))
 166                 return;
 167
 168         ubsan_prologue(&data->location, type_is_signed(type) ?
 169                         "signed-integer-overflow" :
 170                         "unsigned-integer-overflow");
 171
 172         val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
 173         val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
 174         pr_err("%s %c %s cannot be represented in type %s\n",
 175                 lhs_val_str,
 176                 op,
 177                 rhs_val_str,
 178                 type->type_name);
 179
 180         ubsan_epilogue();
 181 }
 182
 183 void __ubsan_handle_add_overflow(void *data,
 184                                 void *lhs, void *rhs)
 185 {
 186
 187         handle_overflow(data, lhs, rhs, '+');
 188 }
 189 EXPORT_SYMBOL(__ubsan_handle_add_overflow);
 190
 191 void __ubsan_handle_sub_overflow(void *data,
 192                                 void *lhs, void *rhs)
 193 {
 194         handle_overflow(data, lhs, rhs, '-');
 195 }
 196 EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
 197
 198 void __ubsan_handle_mul_overflow(void *data,
 199                                 void *lhs, void *rhs)
 200 {
 201         handle_overflow(data, lhs, rhs, '*');
 202 }
 203 EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
 204
 205 void __ubsan_handle_negate_overflow(void *_data, void *old_val)
 206 {
 207         struct overflow_data *data = _data;
 208         char old_val_str[VALUE_LENGTH];
 209
 210         if (suppress_report(&data->location))
 211                 return;
 212
 213         ubsan_prologue(&data->location, "negation-overflow");
 214
 215         val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
 216
 217         pr_err("negation of %s cannot be represented in type %s:\n",
 218                 old_val_str, data->type->type_name);
 219
 220         ubsan_epilogue();
 221 }
 222 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
 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
 408         if (suppress_report(&data->location))
 409                 return;
 410
 411         ubsan_prologue(&data->location, "invalid-load");
 412
 413         val_to_string(val_str, sizeof(val_str), data->type, val);
 414
 415         pr_err("load of value %s is not a valid value for type %s\n",
 416                 val_str, data->type->type_name);
 417
 418         ubsan_epilogue();
 419 }
 420 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
 421
 422 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
 423                                          unsigned long align,
 424                                          unsigned long offset);
 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);