ubsan.c 10 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423
// SPDX-License-Identifier: GPL-2.0-only
/*
 * UBSAN error reporting functions
 *
 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
 */

#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/uaccess.h>

#include "ubsan.h"

const char *type_check_kinds[] = {
	"load of",
	"store to",
	"reference binding to",
	"member access within",
	"member call on",
	"constructor call on",
	"downcast of",
	"downcast of"
};

#define REPORTED_BIT 31

#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
#define COLUMN_MASK (~(1U << REPORTED_BIT))
#define LINE_MASK   (~0U)
#else
#define COLUMN_MASK   (~0U)
#define LINE_MASK (~(1U << REPORTED_BIT))
#endif

#define VALUE_LENGTH 40

static bool was_reported(struct source_location *location)
{
	return test_and_set_bit(REPORTED_BIT, &location->reported);
}

static void print_source_location(const char *prefix,
				struct source_location *loc)
{
	pr_err("%s %s:%d:%d\n", prefix, loc->file_name,
		loc->line & LINE_MASK, loc->column & COLUMN_MASK);
}

static bool suppress_report(struct source_location *loc)
{
	return current->in_ubsan || was_reported(loc);
}

static bool type_is_int(struct type_descriptor *type)
{
	return type->type_kind == type_kind_int;
}

static bool type_is_signed(struct type_descriptor *type)
{
	WARN_ON(!type_is_int(type));
	return  type->type_info & 1;
}

static unsigned type_bit_width(struct type_descriptor *type)
{
	return 1 << (type->type_info >> 1);
}

static bool is_inline_int(struct type_descriptor *type)
{
	unsigned inline_bits = sizeof(unsigned long)*8;
	unsigned bits = type_bit_width(type);

	WARN_ON(!type_is_int(type));

	return bits <= inline_bits;
}

static s_max get_signed_val(struct type_descriptor *type, void *val)
{
	if (is_inline_int(type)) {
		unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
		unsigned long ulong_val = (unsigned long)val;

		return ((s_max)ulong_val) << extra_bits >> extra_bits;
	}

	if (type_bit_width(type) == 64)
		return *(s64 *)val;

	return *(s_max *)val;
}

static bool val_is_negative(struct type_descriptor *type, void *val)
{
	return type_is_signed(type) && get_signed_val(type, val) < 0;
}

static u_max get_unsigned_val(struct type_descriptor *type, void *val)
{
	if (is_inline_int(type))
		return (unsigned long)val;

	if (type_bit_width(type) == 64)
		return *(u64 *)val;

	return *(u_max *)val;
}

static void val_to_string(char *str, size_t size, struct type_descriptor *type,
			void *value)
{
	if (type_is_int(type)) {
		if (type_bit_width(type) == 128) {
#if defined(CONFIG_ARCH_SUPPORTS_INT128)
			u_max val = get_unsigned_val(type, value);

			scnprintf(str, size, "0x%08x%08x%08x%08x",
				(u32)(val >> 96),
				(u32)(val >> 64),
				(u32)(val >> 32),
				(u32)(val));
#else
			WARN_ON(1);
#endif
		} else if (type_is_signed(type)) {
			scnprintf(str, size, "%lld",
				(s64)get_signed_val(type, value));
		} else {
			scnprintf(str, size, "%llu",
				(u64)get_unsigned_val(type, value));
		}
	}
}

static void ubsan_prologue(struct source_location *location)
{
	current->in_ubsan++;

	pr_err("========================================"
		"========================================\n");
	print_source_location("UBSAN: Undefined behaviour in", location);
}

static void ubsan_epilogue(void)
{
	dump_stack();
	pr_err("========================================"
		"========================================\n");

	current->in_ubsan--;
}

static void handle_overflow(struct overflow_data *data, void *lhs,
			void *rhs, char op)
{

	struct type_descriptor *type = data->type;
	char lhs_val_str[VALUE_LENGTH];
	char rhs_val_str[VALUE_LENGTH];

	if (suppress_report(&data->location))
		return;

	ubsan_prologue(&data->location);

	val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
	val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
	pr_err("%s integer overflow:\n",
		type_is_signed(type) ? "signed" : "unsigned");
	pr_err("%s %c %s cannot be represented in type %s\n",
		lhs_val_str,
		op,
		rhs_val_str,
		type->type_name);

	ubsan_epilogue();
}

void __ubsan_handle_add_overflow(struct overflow_data *data,
				void *lhs, void *rhs)
{

	handle_overflow(data, lhs, rhs, '+');
}
EXPORT_SYMBOL(__ubsan_handle_add_overflow);

void __ubsan_handle_sub_overflow(struct overflow_data *data,
				void *lhs, void *rhs)
{
	handle_overflow(data, lhs, rhs, '-');
}
EXPORT_SYMBOL(__ubsan_handle_sub_overflow);

void __ubsan_handle_mul_overflow(struct overflow_data *data,
				void *lhs, void *rhs)
{
	handle_overflow(data, lhs, rhs, '*');
}
EXPORT_SYMBOL(__ubsan_handle_mul_overflow);

void __ubsan_handle_negate_overflow(struct overflow_data *data,
				void *old_val)
{
	char old_val_str[VALUE_LENGTH];

	if (suppress_report(&data->location))
		return;

	ubsan_prologue(&data->location);

	val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);

	pr_err("negation of %s cannot be represented in type %s:\n",
		old_val_str, data->type->type_name);

	ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_negate_overflow);


void __ubsan_handle_divrem_overflow(struct overflow_data *data,
				void *lhs, void *rhs)
{
	char rhs_val_str[VALUE_LENGTH];

	if (suppress_report(&data->location))
		return;

	ubsan_prologue(&data->location);

	val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);

	if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
		pr_err("division of %s by -1 cannot be represented in type %s\n",
			rhs_val_str, data->type->type_name);
	else
		pr_err("division by zero\n");

	ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);

static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
{
	if (suppress_report(data->location))
		return;

	ubsan_prologue(data->location);

	pr_err("%s null pointer of type %s\n",
		type_check_kinds[data->type_check_kind],
		data->type->type_name);

	ubsan_epilogue();
}

static void handle_misaligned_access(struct type_mismatch_data_common *data,
				unsigned long ptr)
{
	if (suppress_report(data->location))
		return;

	ubsan_prologue(data->location);

	pr_err("%s misaligned address %p for type %s\n",
		type_check_kinds[data->type_check_kind],
		(void *)ptr, data->type->type_name);
	pr_err("which requires %ld byte alignment\n", data->alignment);

	ubsan_epilogue();
}

static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
					unsigned long ptr)
{
	if (suppress_report(data->location))
		return;

	ubsan_prologue(data->location);
	pr_err("%s address %p with insufficient space\n",
		type_check_kinds[data->type_check_kind],
		(void *) ptr);
	pr_err("for an object of type %s\n", data->type->type_name);
	ubsan_epilogue();
}

static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
				unsigned long ptr)
{
	unsigned long flags = user_access_save();

	if (!ptr)
		handle_null_ptr_deref(data);
	else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
		handle_misaligned_access(data, ptr);
	else
		handle_object_size_mismatch(data, ptr);

	user_access_restore(flags);
}

void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
				void *ptr)
{
	struct type_mismatch_data_common common_data = {
		.location = &data->location,
		.type = data->type,
		.alignment = data->alignment,
		.type_check_kind = data->type_check_kind
	};

	ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
}
EXPORT_SYMBOL(__ubsan_handle_type_mismatch);

void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
				void *ptr)
{

	struct type_mismatch_data_common common_data = {
		.location = &data->location,
		.type = data->type,
		.alignment = 1UL << data->log_alignment,
		.type_check_kind = data->type_check_kind
	};

	ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
}
EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);

void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index)
{
	char index_str[VALUE_LENGTH];

	if (suppress_report(&data->location))
		return;

	ubsan_prologue(&data->location);

	val_to_string(index_str, sizeof(index_str), data->index_type, index);
	pr_err("index %s is out of range for type %s\n", index_str,
		data->array_type->type_name);
	ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);

void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
					void *lhs, void *rhs)
{
	struct type_descriptor *rhs_type = data->rhs_type;
	struct type_descriptor *lhs_type = data->lhs_type;
	char rhs_str[VALUE_LENGTH];
	char lhs_str[VALUE_LENGTH];
	unsigned long ua_flags = user_access_save();

	if (suppress_report(&data->location))
		goto out;

	ubsan_prologue(&data->location);

	val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
	val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);

	if (val_is_negative(rhs_type, rhs))
		pr_err("shift exponent %s is negative\n", rhs_str);

	else if (get_unsigned_val(rhs_type, rhs) >=
		type_bit_width(lhs_type))
		pr_err("shift exponent %s is too large for %u-bit type %s\n",
			rhs_str,
			type_bit_width(lhs_type),
			lhs_type->type_name);
	else if (val_is_negative(lhs_type, lhs))
		pr_err("left shift of negative value %s\n",
			lhs_str);
	else
		pr_err("left shift of %s by %s places cannot be"
			" represented in type %s\n",
			lhs_str, rhs_str,
			lhs_type->type_name);

	ubsan_epilogue();
out:
	user_access_restore(ua_flags);
}
EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);


void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
{
	ubsan_prologue(&data->location);
	pr_err("calling __builtin_unreachable()\n");
	ubsan_epilogue();
	panic("can't return from __builtin_unreachable()");
}
EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);

void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
				void *val)
{
	char val_str[VALUE_LENGTH];

	if (suppress_report(&data->location))
		return;

	ubsan_prologue(&data->location);

	val_to_string(val_str, sizeof(val_str), data->type, val);

	pr_err("load of value %s is not a valid value for type %s\n",
		val_str, data->type->type_name);

	ubsan_epilogue();
}
EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);