Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/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 
 21 #include "ubsan.h"
 22 
 23 const char *type_check_kinds[] = {
 24         "load of",
 25         "store to",
 26         "reference binding to",
 27         "member access within",
 28         "member call on",
 29         "constructor call on",
 30         "downcast of",
 31         "downcast of"
 32 };
 33 
 34 #define REPORTED_BIT 31
 35 
 36 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
 37 #define COLUMN_MASK (~(1U << REPORTED_BIT))
 38 #define LINE_MASK   (~0U)
 39 #else
 40 #define COLUMN_MASK   (~0U)
 41 #define LINE_MASK (~(1U << REPORTED_BIT))
 42 #endif
 43 
 44 #define VALUE_LENGTH 40
 45 
 46 static bool was_reported(struct source_location *location)
 47 {
 48         return test_and_set_bit(REPORTED_BIT, &location->reported);
 49 }
 50 
 51 static void print_source_location(const char *prefix,
 52                                 struct source_location *loc)
 53 {
 54         pr_err("%s %s:%d:%d\n", prefix, loc->file_name,
 55                 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
 56 }
 57 
 58 static bool suppress_report(struct source_location *loc)
 59 {
 60         return current->in_ubsan || was_reported(loc);
 61 }
 62 
 63 static bool type_is_int(struct type_descriptor *type)
 64 {
 65         return type->type_kind == type_kind_int;
 66 }
 67 
 68 static bool type_is_signed(struct type_descriptor *type)
 69 {
 70         WARN_ON(!type_is_int(type));
 71         return  type->type_info & 1;
 72 }
 73 
 74 static unsigned type_bit_width(struct type_descriptor *type)
 75 {
 76         return 1 << (type->type_info >> 1);
 77 }
 78 
 79 static bool is_inline_int(struct type_descriptor *type)
 80 {
 81         unsigned inline_bits = sizeof(unsigned long)*8;
 82         unsigned bits = type_bit_width(type);
 83 
 84         WARN_ON(!type_is_int(type));
 85 
 86         return bits <= inline_bits;
 87 }
 88 
 89 static s_max get_signed_val(struct type_descriptor *type, unsigned long val)
 90 {
 91         if (is_inline_int(type)) {
 92                 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
 93                 return ((s_max)val) << extra_bits >> extra_bits;
 94         }
 95 
 96         if (type_bit_width(type) == 64)
 97                 return *(s64 *)val;
 98 
 99         return *(s_max *)val;
100 }
101 
102 static bool val_is_negative(struct type_descriptor *type, unsigned long val)
103 {
104         return type_is_signed(type) && get_signed_val(type, val) < 0;
105 }
106 
107 static u_max get_unsigned_val(struct type_descriptor *type, unsigned long val)
108 {
109         if (is_inline_int(type))
110                 return val;
111 
112         if (type_bit_width(type) == 64)
113                 return *(u64 *)val;
114 
115         return *(u_max *)val;
116 }
117 
118 static void val_to_string(char *str, size_t size, struct type_descriptor *type,
119         unsigned long value)
120 {
121         if (type_is_int(type)) {
122                 if (type_bit_width(type) == 128) {
123 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
124                         u_max val = get_unsigned_val(type, value);
125 
126                         scnprintf(str, size, "0x%08x%08x%08x%08x",
127                                 (u32)(val >> 96),
128                                 (u32)(val >> 64),
129                                 (u32)(val >> 32),
130                                 (u32)(val));
131 #else
132                         WARN_ON(1);
133 #endif
134                 } else if (type_is_signed(type)) {
135                         scnprintf(str, size, "%lld",
136                                 (s64)get_signed_val(type, value));
137                 } else {
138                         scnprintf(str, size, "%llu",
139                                 (u64)get_unsigned_val(type, value));
140                 }
141         }
142 }
143 
144 static bool location_is_valid(struct source_location *loc)
145 {
146         return loc->file_name != NULL;
147 }
148 
149 static DEFINE_SPINLOCK(report_lock);
150 
151 static void ubsan_prologue(struct source_location *location,
152                         unsigned long *flags)
153 {
154         current->in_ubsan++;
155         spin_lock_irqsave(&report_lock, *flags);
156 
157         pr_err("========================================"
158                 "========================================\n");
159         print_source_location("UBSAN: Undefined behaviour in", location);
160 }
161 
162 static void ubsan_epilogue(unsigned long *flags)
163 {
164         dump_stack();
165         pr_err("========================================"
166                 "========================================\n");
167         spin_unlock_irqrestore(&report_lock, *flags);
168         current->in_ubsan--;
169 }
170 
171 static void handle_overflow(struct overflow_data *data, unsigned long lhs,
172                         unsigned long rhs, char op)
173 {
174 
175         struct type_descriptor *type = data->type;
176         unsigned long flags;
177         char lhs_val_str[VALUE_LENGTH];
178         char rhs_val_str[VALUE_LENGTH];
179 
180         if (suppress_report(&data->location))
181                 return;
182 
183         ubsan_prologue(&data->location, &flags);
184 
185         val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
186         val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
187         pr_err("%s integer overflow:\n",
188                 type_is_signed(type) ? "signed" : "unsigned");
189         pr_err("%s %c %s cannot be represented in type %s\n",
190                 lhs_val_str,
191                 op,
192                 rhs_val_str,
193                 type->type_name);
194 
195         ubsan_epilogue(&flags);
196 }
197 
198 void __ubsan_handle_add_overflow(struct overflow_data *data,
199                                 unsigned long lhs,
200                                 unsigned long rhs)
201 {
202 
203         handle_overflow(data, lhs, rhs, '+');
204 }
205 EXPORT_SYMBOL(__ubsan_handle_add_overflow);
206 
207 void __ubsan_handle_sub_overflow(struct overflow_data *data,
208                                 unsigned long lhs,
209                                 unsigned long rhs)
210 {
211         handle_overflow(data, lhs, rhs, '-');
212 }
213 EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
214 
215 void __ubsan_handle_mul_overflow(struct overflow_data *data,
216                                 unsigned long lhs,
217                                 unsigned long rhs)
218 {
219         handle_overflow(data, lhs, rhs, '*');
220 }
221 EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
222 
223 void __ubsan_handle_negate_overflow(struct overflow_data *data,
224                                 unsigned long old_val)
225 {
226         unsigned long flags;
227         char old_val_str[VALUE_LENGTH];
228 
229         if (suppress_report(&data->location))
230                 return;
231 
232         ubsan_prologue(&data->location, &flags);
233 
234         val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
235 
236         pr_err("negation of %s cannot be represented in type %s:\n",
237                 old_val_str, data->type->type_name);
238 
239         ubsan_epilogue(&flags);
240 }
241 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
242 
243 
244 void __ubsan_handle_divrem_overflow(struct overflow_data *data,
245                                 unsigned long lhs,
246                                 unsigned long rhs)
247 {
248         unsigned long flags;
249         char rhs_val_str[VALUE_LENGTH];
250 
251         if (suppress_report(&data->location))
252                 return;
253 
254         ubsan_prologue(&data->location, &flags);
255 
256         val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
257 
258         if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
259                 pr_err("division of %s by -1 cannot be represented in type %s\n",
260                         rhs_val_str, data->type->type_name);
261         else
262                 pr_err("division by zero\n");
263 
264         ubsan_epilogue(&flags);
265 }
266 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
267 
268 static void handle_null_ptr_deref(struct type_mismatch_data *data)
269 {
270         unsigned long flags;
271 
272         if (suppress_report(&data->location))
273                 return;
274 
275         ubsan_prologue(&data->location, &flags);
276 
277         pr_err("%s null pointer of type %s\n",
278                 type_check_kinds[data->type_check_kind],
279                 data->type->type_name);
280 
281         ubsan_epilogue(&flags);
282 }
283 
284 static void handle_missaligned_access(struct type_mismatch_data *data,
285                                 unsigned long ptr)
286 {
287         unsigned long flags;
288 
289         if (suppress_report(&data->location))
290                 return;
291 
292         ubsan_prologue(&data->location, &flags);
293 
294         pr_err("%s misaligned address %p for type %s\n",
295                 type_check_kinds[data->type_check_kind],
296                 (void *)ptr, data->type->type_name);
297         pr_err("which requires %ld byte alignment\n", data->alignment);
298 
299         ubsan_epilogue(&flags);
300 }
301 
302 static void handle_object_size_mismatch(struct type_mismatch_data *data,
303                                         unsigned long ptr)
304 {
305         unsigned long flags;
306 
307         if (suppress_report(&data->location))
308                 return;
309 
310         ubsan_prologue(&data->location, &flags);
311         pr_err("%s address %p with insufficient space\n",
312                 type_check_kinds[data->type_check_kind],
313                 (void *) ptr);
314         pr_err("for an object of type %s\n", data->type->type_name);
315         ubsan_epilogue(&flags);
316 }
317 
318 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
319                                 unsigned long ptr)
320 {
321 
322         if (!ptr)
323                 handle_null_ptr_deref(data);
324         else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
325                 handle_missaligned_access(data, ptr);
326         else
327                 handle_object_size_mismatch(data, ptr);
328 }
329 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
330 
331 void __ubsan_handle_nonnull_return(struct nonnull_return_data *data)
332 {
333         unsigned long flags;
334 
335         if (suppress_report(&data->location))
336                 return;
337 
338         ubsan_prologue(&data->location, &flags);
339 
340         pr_err("null pointer returned from function declared to never return null\n");
341 
342         if (location_is_valid(&data->attr_location))
343                 print_source_location("returns_nonnull attribute specified in",
344                                 &data->attr_location);
345 
346         ubsan_epilogue(&flags);
347 }
348 EXPORT_SYMBOL(__ubsan_handle_nonnull_return);
349 
350 void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data,
351                                         unsigned long bound)
352 {
353         unsigned long flags;
354         char bound_str[VALUE_LENGTH];
355 
356         if (suppress_report(&data->location))
357                 return;
358 
359         ubsan_prologue(&data->location, &flags);
360 
361         val_to_string(bound_str, sizeof(bound_str), data->type, bound);
362         pr_err("variable length array bound value %s <= 0\n", bound_str);
363 
364         ubsan_epilogue(&flags);
365 }
366 EXPORT_SYMBOL(__ubsan_handle_vla_bound_not_positive);
367 
368 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data,
369                                 unsigned long index)
370 {
371         unsigned long flags;
372         char index_str[VALUE_LENGTH];
373 
374         if (suppress_report(&data->location))
375                 return;
376 
377         ubsan_prologue(&data->location, &flags);
378 
379         val_to_string(index_str, sizeof(index_str), data->index_type, index);
380         pr_err("index %s is out of range for type %s\n", index_str,
381                 data->array_type->type_name);
382         ubsan_epilogue(&flags);
383 }
384 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
385 
386 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
387                                         unsigned long lhs, unsigned long rhs)
388 {
389         unsigned long flags;
390         struct type_descriptor *rhs_type = data->rhs_type;
391         struct type_descriptor *lhs_type = data->lhs_type;
392         char rhs_str[VALUE_LENGTH];
393         char lhs_str[VALUE_LENGTH];
394 
395         if (suppress_report(&data->location))
396                 return;
397 
398         ubsan_prologue(&data->location, &flags);
399 
400         val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
401         val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
402 
403         if (val_is_negative(rhs_type, rhs))
404                 pr_err("shift exponent %s is negative\n", rhs_str);
405 
406         else if (get_unsigned_val(rhs_type, rhs) >=
407                 type_bit_width(lhs_type))
408                 pr_err("shift exponent %s is too large for %u-bit type %s\n",
409                         rhs_str,
410                         type_bit_width(lhs_type),
411                         lhs_type->type_name);
412         else if (val_is_negative(lhs_type, lhs))
413                 pr_err("left shift of negative value %s\n",
414                         lhs_str);
415         else
416                 pr_err("left shift of %s by %s places cannot be"
417                         " represented in type %s\n",
418                         lhs_str, rhs_str,
419                         lhs_type->type_name);
420 
421         ubsan_epilogue(&flags);
422 }
423 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
424 
425 
426 void __noreturn
427 __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
428 {
429         unsigned long flags;
430 
431         ubsan_prologue(&data->location, &flags);
432         pr_err("calling __builtin_unreachable()\n");
433         ubsan_epilogue(&flags);
434         panic("can't return from __builtin_unreachable()");
435 }
436 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
437 
438 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
439                                 unsigned long val)
440 {
441         unsigned long flags;
442         char val_str[VALUE_LENGTH];
443 
444         if (suppress_report(&data->location))
445                 return;
446 
447         ubsan_prologue(&data->location, &flags);
448 
449         val_to_string(val_str, sizeof(val_str), data->type, val);
450 
451         pr_err("load of value %s is not a valid value for type %s\n",
452                 val_str, data->type->type_name);
453 
454         ubsan_epilogue(&flags);
455 }
456 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
457 

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