Merge branch 'for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu
[sfrench/cifs-2.6.git] / lib / ubsan.c
1 /*
2  * UBSAN error reporting functions
3  *
4  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
5  * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  */
12
13 #include <linux/bitops.h>
14 #include <linux/bug.h>
15 #include <linux/ctype.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/types.h>
19 #include <linux/sched.h>
20 #include <linux/uaccess.h>
21
22 #include "ubsan.h"
23
24 const char *type_check_kinds[] = {
25         "load of",
26         "store to",
27         "reference binding to",
28         "member access within",
29         "member call on",
30         "constructor call on",
31         "downcast of",
32         "downcast of"
33 };
34
35 #define REPORTED_BIT 31
36
37 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
38 #define COLUMN_MASK (~(1U << REPORTED_BIT))
39 #define LINE_MASK   (~0U)
40 #else
41 #define COLUMN_MASK   (~0U)
42 #define LINE_MASK (~(1U << REPORTED_BIT))
43 #endif
44
45 #define VALUE_LENGTH 40
46
47 static bool was_reported(struct source_location *location)
48 {
49         return test_and_set_bit(REPORTED_BIT, &location->reported);
50 }
51
52 static void print_source_location(const char *prefix,
53                                 struct source_location *loc)
54 {
55         pr_err("%s %s:%d:%d\n", prefix, loc->file_name,
56                 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
57 }
58
59 static bool suppress_report(struct source_location *loc)
60 {
61         return current->in_ubsan || was_reported(loc);
62 }
63
64 static bool type_is_int(struct type_descriptor *type)
65 {
66         return type->type_kind == type_kind_int;
67 }
68
69 static bool type_is_signed(struct type_descriptor *type)
70 {
71         WARN_ON(!type_is_int(type));
72         return  type->type_info & 1;
73 }
74
75 static unsigned type_bit_width(struct type_descriptor *type)
76 {
77         return 1 << (type->type_info >> 1);
78 }
79
80 static bool is_inline_int(struct type_descriptor *type)
81 {
82         unsigned inline_bits = sizeof(unsigned long)*8;
83         unsigned bits = type_bit_width(type);
84
85         WARN_ON(!type_is_int(type));
86
87         return bits <= inline_bits;
88 }
89
90 static s_max get_signed_val(struct type_descriptor *type, void *val)
91 {
92         if (is_inline_int(type)) {
93                 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
94                 unsigned long ulong_val = (unsigned long)val;
95
96                 return ((s_max)ulong_val) << extra_bits >> extra_bits;
97         }
98
99         if (type_bit_width(type) == 64)
100                 return *(s64 *)val;
101
102         return *(s_max *)val;
103 }
104
105 static bool val_is_negative(struct type_descriptor *type, void *val)
106 {
107         return type_is_signed(type) && get_signed_val(type, val) < 0;
108 }
109
110 static u_max get_unsigned_val(struct type_descriptor *type, void *val)
111 {
112         if (is_inline_int(type))
113                 return (unsigned long)val;
114
115         if (type_bit_width(type) == 64)
116                 return *(u64 *)val;
117
118         return *(u_max *)val;
119 }
120
121 static void val_to_string(char *str, size_t size, struct type_descriptor *type,
122                         void *value)
123 {
124         if (type_is_int(type)) {
125                 if (type_bit_width(type) == 128) {
126 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
127                         u_max val = get_unsigned_val(type, value);
128
129                         scnprintf(str, size, "0x%08x%08x%08x%08x",
130                                 (u32)(val >> 96),
131                                 (u32)(val >> 64),
132                                 (u32)(val >> 32),
133                                 (u32)(val));
134 #else
135                         WARN_ON(1);
136 #endif
137                 } else if (type_is_signed(type)) {
138                         scnprintf(str, size, "%lld",
139                                 (s64)get_signed_val(type, value));
140                 } else {
141                         scnprintf(str, size, "%llu",
142                                 (u64)get_unsigned_val(type, value));
143                 }
144         }
145 }
146
147 static DEFINE_SPINLOCK(report_lock);
148
149 static void ubsan_prologue(struct source_location *location,
150                         unsigned long *flags)
151 {
152         current->in_ubsan++;
153         spin_lock_irqsave(&report_lock, *flags);
154
155         pr_err("========================================"
156                 "========================================\n");
157         print_source_location("UBSAN: Undefined behaviour in", location);
158 }
159
160 static void ubsan_epilogue(unsigned long *flags)
161 {
162         dump_stack();
163         pr_err("========================================"
164                 "========================================\n");
165         spin_unlock_irqrestore(&report_lock, *flags);
166         current->in_ubsan--;
167 }
168
169 static void handle_overflow(struct overflow_data *data, void *lhs,
170                         void *rhs, char op)
171 {
172
173         struct type_descriptor *type = data->type;
174         unsigned long flags;
175         char lhs_val_str[VALUE_LENGTH];
176         char rhs_val_str[VALUE_LENGTH];
177
178         if (suppress_report(&data->location))
179                 return;
180
181         ubsan_prologue(&data->location, &flags);
182
183         val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
184         val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
185         pr_err("%s integer overflow:\n",
186                 type_is_signed(type) ? "signed" : "unsigned");
187         pr_err("%s %c %s cannot be represented in type %s\n",
188                 lhs_val_str,
189                 op,
190                 rhs_val_str,
191                 type->type_name);
192
193         ubsan_epilogue(&flags);
194 }
195
196 void __ubsan_handle_add_overflow(struct overflow_data *data,
197                                 void *lhs, void *rhs)
198 {
199
200         handle_overflow(data, lhs, rhs, '+');
201 }
202 EXPORT_SYMBOL(__ubsan_handle_add_overflow);
203
204 void __ubsan_handle_sub_overflow(struct overflow_data *data,
205                                 void *lhs, void *rhs)
206 {
207         handle_overflow(data, lhs, rhs, '-');
208 }
209 EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
210
211 void __ubsan_handle_mul_overflow(struct overflow_data *data,
212                                 void *lhs, void *rhs)
213 {
214         handle_overflow(data, lhs, rhs, '*');
215 }
216 EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
217
218 void __ubsan_handle_negate_overflow(struct overflow_data *data,
219                                 void *old_val)
220 {
221         unsigned long flags;
222         char old_val_str[VALUE_LENGTH];
223
224         if (suppress_report(&data->location))
225                 return;
226
227         ubsan_prologue(&data->location, &flags);
228
229         val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
230
231         pr_err("negation of %s cannot be represented in type %s:\n",
232                 old_val_str, data->type->type_name);
233
234         ubsan_epilogue(&flags);
235 }
236 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
237
238
239 void __ubsan_handle_divrem_overflow(struct overflow_data *data,
240                                 void *lhs, void *rhs)
241 {
242         unsigned long flags;
243         char rhs_val_str[VALUE_LENGTH];
244
245         if (suppress_report(&data->location))
246                 return;
247
248         ubsan_prologue(&data->location, &flags);
249
250         val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
251
252         if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
253                 pr_err("division of %s by -1 cannot be represented in type %s\n",
254                         rhs_val_str, data->type->type_name);
255         else
256                 pr_err("division by zero\n");
257
258         ubsan_epilogue(&flags);
259 }
260 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
261
262 static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
263 {
264         unsigned long flags;
265
266         if (suppress_report(data->location))
267                 return;
268
269         ubsan_prologue(data->location, &flags);
270
271         pr_err("%s null pointer of type %s\n",
272                 type_check_kinds[data->type_check_kind],
273                 data->type->type_name);
274
275         ubsan_epilogue(&flags);
276 }
277
278 static void handle_misaligned_access(struct type_mismatch_data_common *data,
279                                 unsigned long ptr)
280 {
281         unsigned long flags;
282
283         if (suppress_report(data->location))
284                 return;
285
286         ubsan_prologue(data->location, &flags);
287
288         pr_err("%s misaligned address %p for type %s\n",
289                 type_check_kinds[data->type_check_kind],
290                 (void *)ptr, data->type->type_name);
291         pr_err("which requires %ld byte alignment\n", data->alignment);
292
293         ubsan_epilogue(&flags);
294 }
295
296 static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
297                                         unsigned long ptr)
298 {
299         unsigned long flags;
300
301         if (suppress_report(data->location))
302                 return;
303
304         ubsan_prologue(data->location, &flags);
305         pr_err("%s address %p with insufficient space\n",
306                 type_check_kinds[data->type_check_kind],
307                 (void *) ptr);
308         pr_err("for an object of type %s\n", data->type->type_name);
309         ubsan_epilogue(&flags);
310 }
311
312 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
313                                 unsigned long ptr)
314 {
315         unsigned long flags = user_access_save();
316
317         if (!ptr)
318                 handle_null_ptr_deref(data);
319         else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
320                 handle_misaligned_access(data, ptr);
321         else
322                 handle_object_size_mismatch(data, ptr);
323
324         user_access_restore(flags);
325 }
326
327 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
328                                 void *ptr)
329 {
330         struct type_mismatch_data_common common_data = {
331                 .location = &data->location,
332                 .type = data->type,
333                 .alignment = data->alignment,
334                 .type_check_kind = data->type_check_kind
335         };
336
337         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
338 }
339 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
340
341 void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
342                                 void *ptr)
343 {
344
345         struct type_mismatch_data_common common_data = {
346                 .location = &data->location,
347                 .type = data->type,
348                 .alignment = 1UL << data->log_alignment,
349                 .type_check_kind = data->type_check_kind
350         };
351
352         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
353 }
354 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
355
356 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index)
357 {
358         unsigned long flags;
359         char index_str[VALUE_LENGTH];
360
361         if (suppress_report(&data->location))
362                 return;
363
364         ubsan_prologue(&data->location, &flags);
365
366         val_to_string(index_str, sizeof(index_str), data->index_type, index);
367         pr_err("index %s is out of range for type %s\n", index_str,
368                 data->array_type->type_name);
369         ubsan_epilogue(&flags);
370 }
371 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
372
373 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
374                                         void *lhs, void *rhs)
375 {
376         unsigned long flags;
377         struct type_descriptor *rhs_type = data->rhs_type;
378         struct type_descriptor *lhs_type = data->lhs_type;
379         char rhs_str[VALUE_LENGTH];
380         char lhs_str[VALUE_LENGTH];
381
382         if (suppress_report(&data->location))
383                 return;
384
385         ubsan_prologue(&data->location, &flags);
386
387         val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
388         val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
389
390         if (val_is_negative(rhs_type, rhs))
391                 pr_err("shift exponent %s is negative\n", rhs_str);
392
393         else if (get_unsigned_val(rhs_type, rhs) >=
394                 type_bit_width(lhs_type))
395                 pr_err("shift exponent %s is too large for %u-bit type %s\n",
396                         rhs_str,
397                         type_bit_width(lhs_type),
398                         lhs_type->type_name);
399         else if (val_is_negative(lhs_type, lhs))
400                 pr_err("left shift of negative value %s\n",
401                         lhs_str);
402         else
403                 pr_err("left shift of %s by %s places cannot be"
404                         " represented in type %s\n",
405                         lhs_str, rhs_str,
406                         lhs_type->type_name);
407
408         ubsan_epilogue(&flags);
409 }
410 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
411
412
413 void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
414 {
415         unsigned long flags;
416
417         ubsan_prologue(&data->location, &flags);
418         pr_err("calling __builtin_unreachable()\n");
419         ubsan_epilogue(&flags);
420         panic("can't return from __builtin_unreachable()");
421 }
422 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
423
424 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
425                                 void *val)
426 {
427         unsigned long flags;
428         char val_str[VALUE_LENGTH];
429
430         if (suppress_report(&data->location))
431                 return;
432
433         ubsan_prologue(&data->location, &flags);
434
435         val_to_string(val_str, sizeof(val_str), data->type, val);
436
437         pr_err("load of value %s is not a valid value for type %s\n",
438                 val_str, data->type->type_name);
439
440         ubsan_epilogue(&flags);
441 }
442 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);