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, addr: &location->reported);
113}
114
115static bool suppress_report(struct source_location *loc)
116{
117 return current->in_ubsan || was_reported(location: 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, val: value);
184
185 scnprintf(buf: str, size, fmt: "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(buf: str, size, fmt: "%lld",
195 (s64)get_signed_val(type, val: value));
196 } else {
197 scnprintf(buf: str, size, fmt: "%llu",
198 (u64)get_unsigned_val(type, val: value));
199 }
200 }
201}
202
203static void ubsan_prologue(struct source_location *loc, const char *reason)
204{
205 current->in_ubsan++;
206
207 pr_err("========================================"
208 "========================================\n");
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_err("========================================"
219 "========================================\n");
220
221 current->in_ubsan--;
222
223 check_panic_on_warn(origin: "UBSAN");
224}
225
226void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
227{
228 struct overflow_data *data = _data;
229 char rhs_val_str[VALUE_LENGTH];
230
231 if (suppress_report(loc: &data->location))
232 return;
233
234 ubsan_prologue(loc: &data->location, reason: "division-overflow");
235
236 val_to_string(str: rhs_val_str, size: sizeof(rhs_val_str), type: data->type, value: rhs);
237
238 if (type_is_signed(type: data->type) && get_signed_val(type: data->type, val: rhs) == -1)
239 pr_err("division of %s by -1 cannot be represented in type %s\n",
240 rhs_val_str, data->type->type_name);
241 else
242 pr_err("division by zero\n");
243
244 ubsan_epilogue();
245}
246EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
247
248static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
249{
250 if (suppress_report(loc: data->location))
251 return;
252
253 ubsan_prologue(loc: data->location, reason: "null-ptr-deref");
254
255 pr_err("%s null pointer of type %s\n",
256 type_check_kinds[data->type_check_kind],
257 data->type->type_name);
258
259 ubsan_epilogue();
260}
261
262static void handle_misaligned_access(struct type_mismatch_data_common *data,
263 unsigned long ptr)
264{
265 if (suppress_report(loc: data->location))
266 return;
267
268 ubsan_prologue(loc: data->location, reason: "misaligned-access");
269
270 pr_err("%s misaligned address %p for type %s\n",
271 type_check_kinds[data->type_check_kind],
272 (void *)ptr, data->type->type_name);
273 pr_err("which requires %ld byte alignment\n", data->alignment);
274
275 ubsan_epilogue();
276}
277
278static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
279 unsigned long ptr)
280{
281 if (suppress_report(loc: data->location))
282 return;
283
284 ubsan_prologue(loc: data->location, reason: "object-size-mismatch");
285 pr_err("%s address %p with insufficient space\n",
286 type_check_kinds[data->type_check_kind],
287 (void *) ptr);
288 pr_err("for an object of type %s\n", data->type->type_name);
289 ubsan_epilogue();
290}
291
292static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
293 unsigned long ptr)
294{
295 unsigned long flags = user_access_save();
296
297 if (!ptr)
298 handle_null_ptr_deref(data);
299 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
300 handle_misaligned_access(data, ptr);
301 else
302 handle_object_size_mismatch(data, ptr);
303
304 user_access_restore(flags);
305}
306
307void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
308 void *ptr)
309{
310 struct type_mismatch_data_common common_data = {
311 .location = &data->location,
312 .type = data->type,
313 .alignment = data->alignment,
314 .type_check_kind = data->type_check_kind
315 };
316
317 ubsan_type_mismatch_common(data: &common_data, ptr: (unsigned long)ptr);
318}
319EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
320
321void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
322{
323 struct type_mismatch_data_v1 *data = _data;
324 struct type_mismatch_data_common common_data = {
325 .location = &data->location,
326 .type = data->type,
327 .alignment = 1UL << data->log_alignment,
328 .type_check_kind = data->type_check_kind
329 };
330
331 ubsan_type_mismatch_common(data: &common_data, ptr: (unsigned long)ptr);
332}
333EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
334
335void __ubsan_handle_out_of_bounds(void *_data, void *index)
336{
337 struct out_of_bounds_data *data = _data;
338 char index_str[VALUE_LENGTH];
339
340 if (suppress_report(loc: &data->location))
341 return;
342
343 ubsan_prologue(loc: &data->location, reason: "array-index-out-of-bounds");
344
345 val_to_string(str: index_str, size: sizeof(index_str), type: data->index_type, value: index);
346 pr_err("index %s is out of range for type %s\n", index_str,
347 data->array_type->type_name);
348 ubsan_epilogue();
349}
350EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
351
352void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
353{
354 struct shift_out_of_bounds_data *data = _data;
355 struct type_descriptor *rhs_type = data->rhs_type;
356 struct type_descriptor *lhs_type = data->lhs_type;
357 char rhs_str[VALUE_LENGTH];
358 char lhs_str[VALUE_LENGTH];
359 unsigned long ua_flags = user_access_save();
360
361 if (suppress_report(loc: &data->location))
362 goto out;
363
364 ubsan_prologue(loc: &data->location, reason: "shift-out-of-bounds");
365
366 val_to_string(str: rhs_str, size: sizeof(rhs_str), type: rhs_type, value: rhs);
367 val_to_string(str: lhs_str, size: sizeof(lhs_str), type: lhs_type, value: lhs);
368
369 if (val_is_negative(type: rhs_type, val: rhs))
370 pr_err("shift exponent %s is negative\n", rhs_str);
371
372 else if (get_unsigned_val(type: rhs_type, val: rhs) >=
373 type_bit_width(type: lhs_type))
374 pr_err("shift exponent %s is too large for %u-bit type %s\n",
375 rhs_str,
376 type_bit_width(lhs_type),
377 lhs_type->type_name);
378 else if (val_is_negative(type: lhs_type, val: lhs))
379 pr_err("left shift of negative value %s\n",
380 lhs_str);
381 else
382 pr_err("left shift of %s by %s places cannot be"
383 " represented in type %s\n",
384 lhs_str, rhs_str,
385 lhs_type->type_name);
386
387 ubsan_epilogue();
388out:
389 user_access_restore(ua_flags);
390}
391EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
392
393
394void __ubsan_handle_builtin_unreachable(void *_data)
395{
396 struct unreachable_data *data = _data;
397 ubsan_prologue(loc: &data->location, reason: "unreachable");
398 pr_err("calling __builtin_unreachable()\n");
399 ubsan_epilogue();
400 panic(fmt: "can't return from __builtin_unreachable()");
401}
402EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
403
404void __ubsan_handle_load_invalid_value(void *_data, void *val)
405{
406 struct invalid_value_data *data = _data;
407 char val_str[VALUE_LENGTH];
408 unsigned long ua_flags = user_access_save();
409
410 if (suppress_report(loc: &data->location))
411 goto out;
412
413 ubsan_prologue(loc: &data->location, reason: "invalid-load");
414
415 val_to_string(str: val_str, size: sizeof(val_str), type: data->type, value: val);
416
417 pr_err("load of value %s is not a valid value for type %s\n",
418 val_str, data->type->type_name);
419
420 ubsan_epilogue();
421out:
422 user_access_restore(ua_flags);
423}
424EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
425
426void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
427 unsigned long align,
428 unsigned long offset)
429{
430 struct alignment_assumption_data *data = _data;
431 unsigned long real_ptr;
432
433 if (suppress_report(loc: &data->location))
434 return;
435
436 ubsan_prologue(loc: &data->location, reason: "alignment-assumption");
437
438 if (offset)
439 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
440 align, offset, data->type->type_name);
441 else
442 pr_err("assumption of %lu byte alignment for pointer of type %s failed",
443 align, data->type->type_name);
444
445 real_ptr = ptr - offset;
446 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
447 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
448 real_ptr & (align - 1));
449
450 ubsan_epilogue();
451}
452EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);
453
454#endif /* !CONFIG_UBSAN_TRAP */
455

source code of linux/lib/ubsan.c