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 #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);