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