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 <linux/ubsan.h>
 18#include <kunit/test-bug.h>
 19
 20#include "ubsan.h"
 21
 22#if defined(CONFIG_UBSAN_TRAP) || defined(CONFIG_UBSAN_KVM_EL2)
 23/*
 24 * Only include matches for UBSAN checks that are actually compiled in.
 25 * The mappings of struct SanitizerKind (the -fsanitize=xxx args) to
 26 * enum SanitizerHandler (the traps) in Clang is in clang/lib/CodeGen/.
 27 */
 28const char *report_ubsan_failure(u32 check_type)
 29{
 30	switch (check_type) {
 31#ifdef CONFIG_UBSAN_BOUNDS
 32	/*
 33	 * SanitizerKind::ArrayBounds and SanitizerKind::LocalBounds
 34	 * emit SanitizerHandler::OutOfBounds.
 35	 */
 36	case ubsan_out_of_bounds:
 37		return "UBSAN: array index out of bounds";
 38#endif
 39#ifdef CONFIG_UBSAN_SHIFT
 40	/*
 41	 * SanitizerKind::ShiftBase and SanitizerKind::ShiftExponent
 42	 * emit SanitizerHandler::ShiftOutOfBounds.
 43	 */
 44	case ubsan_shift_out_of_bounds:
 45		return "UBSAN: shift out of bounds";
 46#endif
 47#if defined(CONFIG_UBSAN_DIV_ZERO) || defined(CONFIG_UBSAN_INTEGER_WRAP)
 48	/*
 49	 * SanitizerKind::IntegerDivideByZero and
 50	 * SanitizerKind::SignedIntegerOverflow emit
 51	 * SanitizerHandler::DivremOverflow.
 52	 */
 53	case ubsan_divrem_overflow:
 54		return "UBSAN: divide/remainder overflow";
 55#endif
 56#ifdef CONFIG_UBSAN_UNREACHABLE
 57	/*
 58	 * SanitizerKind::Unreachable emits
 59	 * SanitizerHandler::BuiltinUnreachable.
 60	 */
 61	case ubsan_builtin_unreachable:
 62		return "UBSAN: unreachable code";
 63#endif
 64#if defined(CONFIG_UBSAN_BOOL) || defined(CONFIG_UBSAN_ENUM)
 65	/*
 66	 * SanitizerKind::Bool and SanitizerKind::Enum emit
 67	 * SanitizerHandler::LoadInvalidValue.
 68	 */
 69	case ubsan_load_invalid_value:
 70		return "UBSAN: loading invalid value";
 71#endif
 72#ifdef CONFIG_UBSAN_ALIGNMENT
 73	/*
 74	 * SanitizerKind::Alignment emits SanitizerHandler::TypeMismatch
 75	 * or SanitizerHandler::AlignmentAssumption.
 76	 */
 77	case ubsan_alignment_assumption:
 78		return "UBSAN: alignment assumption";
 79	case ubsan_type_mismatch:
 80		return "UBSAN: type mismatch";
 81#endif
 82#ifdef CONFIG_UBSAN_INTEGER_WRAP
 83	/*
 84	 * SanitizerKind::SignedIntegerOverflow emits
 85	 * SanitizerHandler::AddOverflow, SanitizerHandler::SubOverflow,
 86	 * or SanitizerHandler::MulOverflow.
 87	 */
 88	case ubsan_add_overflow:
 89		return "UBSAN: integer addition overflow";
 90	case ubsan_sub_overflow:
 91		return "UBSAN: integer subtraction overflow";
 92	case ubsan_mul_overflow:
 93		return "UBSAN: integer multiplication overflow";
 94#endif
 95	default:
 96		return "UBSAN: unrecognized failure code";
 97	}
 98}
 99
100#endif
101
102#ifndef CONFIG_UBSAN_TRAP
103static const char * const type_check_kinds[] = {
104	"load of",
105	"store to",
106	"reference binding to",
107	"member access within",
108	"member call on",
109	"constructor call on",
110	"downcast of",
111	"downcast of"
112};
113
114#define REPORTED_BIT 31
115
116#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
117#define COLUMN_MASK (~(1U << REPORTED_BIT))
118#define LINE_MASK   (~0U)
119#else
120#define COLUMN_MASK   (~0U)
121#define LINE_MASK (~(1U << REPORTED_BIT))
122#endif
123
124#define VALUE_LENGTH 40
125
126static bool was_reported(struct source_location *location)
127{
128	return test_and_set_bit(REPORTED_BIT, &location->reported);
129}
130
131static bool suppress_report(struct source_location *loc)
132{
133	return current->in_ubsan || was_reported(loc);
134}
135
136static bool type_is_int(struct type_descriptor *type)
137{
138	return type->type_kind == type_kind_int;
139}
140
141static bool type_is_signed(struct type_descriptor *type)
142{
143	WARN_ON(!type_is_int(type));
144	return  type->type_info & 1;
145}
146
147static unsigned type_bit_width(struct type_descriptor *type)
148{
149	return 1 << (type->type_info >> 1);
150}
151
152static bool is_inline_int(struct type_descriptor *type)
153{
154	unsigned inline_bits = sizeof(unsigned long)*8;
155	unsigned bits = type_bit_width(type);
156
157	WARN_ON(!type_is_int(type));
158
159	return bits <= inline_bits;
160}
161
162static s_max get_signed_val(struct type_descriptor *type, void *val)
163{
164	if (is_inline_int(type)) {
165		unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
166		unsigned long ulong_val = (unsigned long)val;
167
168		return ((s_max)ulong_val) << extra_bits >> extra_bits;
169	}
170
171	if (type_bit_width(type) == 64)
172		return *(s64 *)val;
173
174	return *(s_max *)val;
175}
176
177static bool val_is_negative(struct type_descriptor *type, void *val)
178{
179	return type_is_signed(type) && get_signed_val(type, val) < 0;
180}
181
182static u_max get_unsigned_val(struct type_descriptor *type, void *val)
183{
184	if (is_inline_int(type))
185		return (unsigned long)val;
186
187	if (type_bit_width(type) == 64)
188		return *(u64 *)val;
189
190	return *(u_max *)val;
191}
192
193static void val_to_string(char *str, size_t size, struct type_descriptor *type,
194			void *value)
195{
196	if (type_is_int(type)) {
197		if (type_bit_width(type) == 128) {
198#if defined(CONFIG_ARCH_SUPPORTS_INT128)
199			u_max val = get_unsigned_val(type, value);
200
201			scnprintf(str, size, "0x%08x%08x%08x%08x",
202				(u32)(val >> 96),
203				(u32)(val >> 64),
204				(u32)(val >> 32),
205				(u32)(val));
206#else
207			WARN_ON(1);
208#endif
209		} else if (type_is_signed(type)) {
210			scnprintf(str, size, "%lld",
211				(s64)get_signed_val(type, value));
212		} else {
213			scnprintf(str, size, "%llu",
214				(u64)get_unsigned_val(type, value));
215		}
216	}
217}
218
219static void ubsan_prologue(struct source_location *loc, const char *reason)
220{
221	current->in_ubsan++;
222
223	pr_warn(CUT_HERE);
224
225	pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
226		loc->line & LINE_MASK, loc->column & COLUMN_MASK);
227
228	kunit_fail_current_test("%s in %s", reason, loc->file_name);
229}
230
231static void ubsan_epilogue(void)
232{
233	dump_stack();
234	pr_warn("---[ end trace ]---\n");
235
236	current->in_ubsan--;
237
238	check_panic_on_warn("UBSAN");
239}
240
241static void handle_overflow(struct overflow_data *data, void *lhs,
242			void *rhs, char op)
243{
244
245	struct type_descriptor *type = data->type;
246	char lhs_val_str[VALUE_LENGTH];
247	char rhs_val_str[VALUE_LENGTH];
248
249	if (suppress_report(&data->location))
250		return;
251
252	ubsan_prologue(&data->location, type_is_signed(type) ?
253			"signed-integer-overflow" :
254			"unsigned-integer-overflow");
255
256	val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
257	val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
258	pr_err("%s %c %s cannot be represented in type %s\n",
259		lhs_val_str,
260		op,
261		rhs_val_str,
262		type->type_name);
263
264	ubsan_epilogue();
265}
266
267void __ubsan_handle_add_overflow(void *data,
268				void *lhs, void *rhs)
269{
270
271	handle_overflow(data, lhs, rhs, '+');
272}
273EXPORT_SYMBOL(__ubsan_handle_add_overflow);
274
275void __ubsan_handle_sub_overflow(void *data,
276				void *lhs, void *rhs)
277{
278	handle_overflow(data, lhs, rhs, '-');
279}
280EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
281
282void __ubsan_handle_mul_overflow(void *data,
283				void *lhs, void *rhs)
284{
285	handle_overflow(data, lhs, rhs, '*');
286}
287EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
288
289void __ubsan_handle_negate_overflow(void *_data, void *old_val)
290{
291	struct overflow_data *data = _data;
292	char old_val_str[VALUE_LENGTH];
293
294	if (suppress_report(&data->location))
295		return;
296
297	ubsan_prologue(&data->location, "negation-overflow");
298
299	val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
300
301	pr_err("negation of %s cannot be represented in type %s:\n",
302		old_val_str, data->type->type_name);
303
304	ubsan_epilogue();
305}
306EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
307
308void __ubsan_handle_implicit_conversion(void *_data, void *from_val, void *to_val)
309{
310	struct implicit_conversion_data *data = _data;
311	char from_val_str[VALUE_LENGTH];
312	char to_val_str[VALUE_LENGTH];
313
314	if (suppress_report(&data->location))
315		return;
316
317	val_to_string(from_val_str, sizeof(from_val_str), data->from_type, from_val);
318	val_to_string(to_val_str, sizeof(to_val_str), data->to_type, to_val);
319
320	ubsan_prologue(&data->location, "implicit-conversion");
321
322	pr_err("cannot represent %s value %s during %s %s, truncated to %s\n",
323		data->from_type->type_name,
324		from_val_str,
325		type_check_kinds[data->type_check_kind],
326		data->to_type->type_name,
327		to_val_str);
328
329	ubsan_epilogue();
330}
331EXPORT_SYMBOL(__ubsan_handle_implicit_conversion);
332
333void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
334{
335	struct overflow_data *data = _data;
336	char lhs_val_str[VALUE_LENGTH];
337
338	if (suppress_report(&data->location))
339		return;
340
341	ubsan_prologue(&data->location, "division-overflow");
342
343	val_to_string(lhs_val_str, sizeof(lhs_val_str), data->type, lhs);
344
345	if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
346		pr_err("division of %s by -1 cannot be represented in type %s\n",
347			lhs_val_str, data->type->type_name);
348	else
349		pr_err("division by zero\n");
350
351	ubsan_epilogue();
352}
353EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
354
355static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
356{
357	if (suppress_report(data->location))
358		return;
359
360	ubsan_prologue(data->location, "null-ptr-deref");
361
362	pr_err("%s null pointer of type %s\n",
363		type_check_kinds[data->type_check_kind],
364		data->type->type_name);
365
366	ubsan_epilogue();
367}
368
369static void handle_misaligned_access(struct type_mismatch_data_common *data,
370				unsigned long ptr)
371{
372	if (suppress_report(data->location))
373		return;
374
375	ubsan_prologue(data->location, "misaligned-access");
376
377	pr_err("%s misaligned address %p for type %s\n",
378		type_check_kinds[data->type_check_kind],
379		(void *)ptr, data->type->type_name);
380	pr_err("which requires %ld byte alignment\n", data->alignment);
381
382	ubsan_epilogue();
383}
384
385static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
386					unsigned long ptr)
387{
388	if (suppress_report(data->location))
389		return;
390
391	ubsan_prologue(data->location, "object-size-mismatch");
392	pr_err("%s address %p with insufficient space\n",
393		type_check_kinds[data->type_check_kind],
394		(void *) ptr);
395	pr_err("for an object of type %s\n", data->type->type_name);
396	ubsan_epilogue();
397}
398
399static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
400				unsigned long ptr)
401{
402	unsigned long flags = user_access_save();
403
404	if (!ptr)
405		handle_null_ptr_deref(data);
406	else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
407		handle_misaligned_access(data, ptr);
408	else
409		handle_object_size_mismatch(data, ptr);
410
411	user_access_restore(flags);
412}
413
414void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
415				void *ptr)
416{
417	struct type_mismatch_data_common common_data = {
418		.location = &data->location,
419		.type = data->type,
420		.alignment = data->alignment,
421		.type_check_kind = data->type_check_kind
422	};
423
424	ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
425}
426EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
427
428void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
429{
430	struct type_mismatch_data_v1 *data = _data;
431	struct type_mismatch_data_common common_data = {
432		.location = &data->location,
433		.type = data->type,
434		.alignment = 1UL << data->log_alignment,
435		.type_check_kind = data->type_check_kind
436	};
437
438	ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
439}
440EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
441
442void __ubsan_handle_out_of_bounds(void *_data, void *index)
443{
444	struct out_of_bounds_data *data = _data;
445	char index_str[VALUE_LENGTH];
446
447	if (suppress_report(&data->location))
448		return;
449
450	ubsan_prologue(&data->location, "array-index-out-of-bounds");
451
452	val_to_string(index_str, sizeof(index_str), data->index_type, index);
453	pr_err("index %s is out of range for type %s\n", index_str,
454		data->array_type->type_name);
455	ubsan_epilogue();
456}
457EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
458
459void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
460{
461	struct shift_out_of_bounds_data *data = _data;
462	struct type_descriptor *rhs_type = data->rhs_type;
463	struct type_descriptor *lhs_type = data->lhs_type;
464	char rhs_str[VALUE_LENGTH];
465	char lhs_str[VALUE_LENGTH];
466	unsigned long ua_flags = user_access_save();
467
468	if (suppress_report(&data->location))
469		goto out;
470
471	ubsan_prologue(&data->location, "shift-out-of-bounds");
472
473	val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
474	val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
475
476	if (val_is_negative(rhs_type, rhs))
477		pr_err("shift exponent %s is negative\n", rhs_str);
478
479	else if (get_unsigned_val(rhs_type, rhs) >=
480		type_bit_width(lhs_type))
481		pr_err("shift exponent %s is too large for %u-bit type %s\n",
482			rhs_str,
483			type_bit_width(lhs_type),
484			lhs_type->type_name);
485	else if (val_is_negative(lhs_type, lhs))
486		pr_err("left shift of negative value %s\n",
487			lhs_str);
488	else
489		pr_err("left shift of %s by %s places cannot be"
490			" represented in type %s\n",
491			lhs_str, rhs_str,
492			lhs_type->type_name);
493
494	ubsan_epilogue();
495out:
496	user_access_restore(ua_flags);
497}
498EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
499
500
501void __ubsan_handle_builtin_unreachable(void *_data)
502{
503	struct unreachable_data *data = _data;
504	ubsan_prologue(&data->location, "unreachable");
505	pr_err("calling __builtin_unreachable()\n");
506	ubsan_epilogue();
507	panic("can't return from __builtin_unreachable()");
508}
509EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
510
511void __ubsan_handle_load_invalid_value(void *_data, void *val)
512{
513	struct invalid_value_data *data = _data;
514	char val_str[VALUE_LENGTH];
515	unsigned long ua_flags = user_access_save();
516
517	if (suppress_report(&data->location))
518		goto out;
519
520	ubsan_prologue(&data->location, "invalid-load");
521
522	val_to_string(val_str, sizeof(val_str), data->type, val);
523
524	pr_err("load of value %s is not a valid value for type %s\n",
525		val_str, data->type->type_name);
526
527	ubsan_epilogue();
528out:
529	user_access_restore(ua_flags);
530}
531EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
532
533void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
534					 unsigned long align,
535					 unsigned long offset)
536{
537	struct alignment_assumption_data *data = _data;
538	unsigned long real_ptr;
539
540	if (suppress_report(&data->location))
541		return;
542
543	ubsan_prologue(&data->location, "alignment-assumption");
544
545	if (offset)
546		pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
547		       align, offset, data->type->type_name);
548	else
549		pr_err("assumption of %lu byte alignment for pointer of type %s failed",
550		       align, data->type->type_name);
551
552	real_ptr = ptr - offset;
553	pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
554	       offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
555	       real_ptr & (align - 1));
556
557	ubsan_epilogue();
558}
559EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);
560
561#endif /* !CONFIG_UBSAN_TRAP */