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
was_reported(struct source_location * location)44 static bool was_reported(struct source_location *location)
45 {
46 return test_and_set_bit(REPORTED_BIT, &location->reported);
47 }
48
suppress_report(struct source_location * loc)49 static bool suppress_report(struct source_location *loc)
50 {
51 return current->in_ubsan || was_reported(loc);
52 }
53
type_is_int(struct type_descriptor * type)54 static bool type_is_int(struct type_descriptor *type)
55 {
56 return type->type_kind == type_kind_int;
57 }
58
type_is_signed(struct type_descriptor * type)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
type_bit_width(struct type_descriptor * type)65 static unsigned type_bit_width(struct type_descriptor *type)
66 {
67 return 1 << (type->type_info >> 1);
68 }
69
is_inline_int(struct type_descriptor * type)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
get_signed_val(struct type_descriptor * type,void * val)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
val_is_negative(struct type_descriptor * type,void * val)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
get_unsigned_val(struct type_descriptor * type,void * val)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
val_to_string(char * str,size_t size,struct type_descriptor * type,void * value)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
ubsan_prologue(struct source_location * loc,const char * reason)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
ubsan_epilogue(void)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
__ubsan_handle_divrem_overflow(void * _data,void * lhs,void * rhs)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
handle_null_ptr_deref(struct type_mismatch_data_common * data)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
handle_misaligned_access(struct type_mismatch_data_common * data,unsigned long ptr)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
handle_object_size_mismatch(struct type_mismatch_data_common * data,unsigned long ptr)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
ubsan_type_mismatch_common(struct type_mismatch_data_common * data,unsigned long ptr)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
__ubsan_handle_type_mismatch(struct type_mismatch_data * data,void * ptr)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
__ubsan_handle_type_mismatch_v1(void * _data,void * ptr)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
__ubsan_handle_out_of_bounds(void * _data,void * index)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
__ubsan_handle_shift_out_of_bounds(void * _data,void * lhs,void * rhs)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
__ubsan_handle_builtin_unreachable(void * _data)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
__ubsan_handle_load_invalid_value(void * _data,void * val)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);
__ubsan_handle_alignment_assumption(void * _data,unsigned long ptr,unsigned long align,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);
388
