1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_FORTIFY_STRING_H_
3 #define _LINUX_FORTIFY_STRING_H_
6 #include <linux/const.h>
7 #include <linux/limits.h>
9 #define __FORTIFY_INLINE extern __always_inline __gnu_inline __overloadable
10 #define __RENAME(x) __asm__(#x)
12 void fortify_panic(const char *name) __noreturn __cold;
13 void __read_overflow(void) __compiletime_error("detected read beyond size of object (1st parameter)");
14 void __read_overflow2(void) __compiletime_error("detected read beyond size of object (2nd parameter)");
15 void __read_overflow2_field(size_t avail, size_t wanted) __compiletime_warning("detected read beyond size of field (2nd parameter); maybe use struct_group()?");
16 void __write_overflow(void) __compiletime_error("detected write beyond size of object (1st parameter)");
17 void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("detected write beyond size of field (1st parameter); maybe use struct_group()?");
19 #define __compiletime_strlen(p) \
21 char *__p = (char *)(p); \
22 size_t __ret = SIZE_MAX; \
23 size_t __p_size = __member_size(p); \
24 if (__p_size != SIZE_MAX && \
25 __builtin_constant_p(*__p)) { \
26 size_t __p_len = __p_size - 1; \
27 if (__builtin_constant_p(__p[__p_len]) && \
28 __p[__p_len] == '\0') \
29 __ret = __builtin_strlen(__p); \
34 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
35 extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
36 extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
37 extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
38 extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
39 extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
40 extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
41 extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
42 extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
43 extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
44 extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
47 #if defined(__SANITIZE_MEMORY__)
49 * For KMSAN builds all memcpy/memset/memmove calls should be replaced by the
50 * corresponding __msan_XXX functions.
52 #include <linux/kmsan_string.h>
53 #define __underlying_memcpy __msan_memcpy
54 #define __underlying_memmove __msan_memmove
55 #define __underlying_memset __msan_memset
57 #define __underlying_memcpy __builtin_memcpy
58 #define __underlying_memmove __builtin_memmove
59 #define __underlying_memset __builtin_memset
62 #define __underlying_memchr __builtin_memchr
63 #define __underlying_memcmp __builtin_memcmp
64 #define __underlying_strcat __builtin_strcat
65 #define __underlying_strcpy __builtin_strcpy
66 #define __underlying_strlen __builtin_strlen
67 #define __underlying_strncat __builtin_strncat
68 #define __underlying_strncpy __builtin_strncpy
72 * unsafe_memcpy - memcpy implementation with no FORTIFY bounds checking
74 * @dst: Destination memory address to write to
75 * @src: Source memory address to read from
76 * @bytes: How many bytes to write to @dst from @src
77 * @justification: Free-form text or comment describing why the use is needed
79 * This should be used for corner cases where the compiler cannot do the
80 * right thing, or during transitions between APIs, etc. It should be used
81 * very rarely, and includes a place for justification detailing where bounds
82 * checking has happened, and why existing solutions cannot be employed.
84 #define unsafe_memcpy(dst, src, bytes, justification) \
85 __underlying_memcpy(dst, src, bytes)
88 * Clang's use of __builtin_*object_size() within inlines needs hinting via
89 * __pass_*object_size(). The preference is to only ever use type 1 (member
90 * size, rather than struct size), but there remain some stragglers using
91 * type 0 that will be converted in the future.
93 #define POS __pass_object_size(1)
94 #define POS0 __pass_object_size(0)
95 #define __struct_size(p) __builtin_object_size(p, 0)
96 #define __member_size(p) __builtin_object_size(p, 1)
98 #define __compiletime_lessthan(bounds, length) ( \
99 __builtin_constant_p((bounds) < (length)) && \
100 (bounds) < (length) \
104 * strncpy - Copy a string to memory with non-guaranteed NUL padding
106 * @p: pointer to destination of copy
107 * @q: pointer to NUL-terminated source string to copy
108 * @size: bytes to write at @p
110 * If strlen(@q) >= @size, the copy of @q will stop after @size bytes,
111 * and @p will NOT be NUL-terminated
113 * If strlen(@q) < @size, following the copy of @q, trailing NUL bytes
114 * will be written to @p until @size total bytes have been written.
116 * Do not use this function. While FORTIFY_SOURCE tries to avoid
117 * over-reads of @q, it cannot defend against writing unterminated
118 * results to @p. Using strncpy() remains ambiguous and fragile.
119 * Instead, please choose an alternative, so that the expectation
120 * of @p's contents is unambiguous:
122 * +--------------------+--------------------+------------+
123 * | **p** needs to be: | padded to **size** | not padded |
124 * +====================+====================+============+
125 * | NUL-terminated | strscpy_pad() | strscpy() |
126 * +--------------------+--------------------+------------+
127 * | not NUL-terminated | strtomem_pad() | strtomem() |
128 * +--------------------+--------------------+------------+
130 * Note strscpy*()'s differing return values for detecting truncation,
131 * and strtomem*()'s expectation that the destination is marked with
132 * __nonstring when it is a character array.
135 __FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3)
136 char *strncpy(char * const POS p, const char *q, __kernel_size_t size)
138 size_t p_size = __member_size(p);
140 if (__compiletime_lessthan(p_size, size))
143 fortify_panic(__func__);
144 return __underlying_strncpy(p, q, size);
148 * strcat - Append a string to an existing string
150 * @p: pointer to NUL-terminated string to append to
151 * @q: pointer to NUL-terminated source string to append from
153 * Do not use this function. While FORTIFY_SOURCE tries to avoid
154 * read and write overflows, this is only possible when the
155 * destination buffer size is known to the compiler. Prefer
156 * building the string with formatting, via scnprintf() or similar.
157 * At the very least, use strncat().
162 __FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2)
163 char *strcat(char * const POS p, const char *q)
165 size_t p_size = __member_size(p);
167 if (p_size == SIZE_MAX)
168 return __underlying_strcat(p, q);
169 if (strlcat(p, q, p_size) >= p_size)
170 fortify_panic(__func__);
174 extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen);
176 * strnlen - Return bounded count of characters in a NUL-terminated string
178 * @p: pointer to NUL-terminated string to count.
179 * @maxlen: maximum number of characters to count.
181 * Returns number of characters in @p (NOT including the final NUL), or
182 * @maxlen, if no NUL has been found up to there.
185 __FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size_t maxlen)
187 size_t p_size = __member_size(p);
188 size_t p_len = __compiletime_strlen(p);
191 /* We can take compile-time actions when maxlen is const. */
192 if (__builtin_constant_p(maxlen) && p_len != SIZE_MAX) {
193 /* If p is const, we can use its compile-time-known len. */
194 if (maxlen >= p_size)
198 /* Do not check characters beyond the end of p. */
199 ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size);
200 if (p_size <= ret && maxlen != ret)
201 fortify_panic(__func__);
206 * Defined after fortified strnlen to reuse it. However, it must still be
207 * possible for strlen() to be used on compile-time strings for use in
208 * static initializers (i.e. as a constant expression).
211 * strlen - Return count of characters in a NUL-terminated string
213 * @p: pointer to NUL-terminated string to count.
215 * Do not use this function unless the string length is known at
216 * compile-time. When @p is unterminated, this function may crash
217 * or return unexpected counts that could lead to memory content
218 * exposures. Prefer strnlen().
220 * Returns number of characters in @p (NOT including the final NUL).
224 __builtin_choose_expr(__is_constexpr(__builtin_strlen(p)), \
225 __builtin_strlen(p), __fortify_strlen(p))
226 __FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1)
227 __kernel_size_t __fortify_strlen(const char * const POS p)
230 size_t p_size = __member_size(p);
232 /* Give up if we don't know how large p is. */
233 if (p_size == SIZE_MAX)
234 return __underlying_strlen(p);
235 ret = strnlen(p, p_size);
237 fortify_panic(__func__);
241 /* Defined after fortified strlen() to reuse it. */
242 extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);
244 * strlcpy - Copy a string into another string buffer
246 * @p: pointer to destination of copy
247 * @q: pointer to NUL-terminated source string to copy
248 * @size: maximum number of bytes to write at @p
250 * If strlen(@q) >= @size, the copy of @q will be truncated at
251 * @size - 1 bytes. @p will always be NUL-terminated.
253 * Do not use this function. While FORTIFY_SOURCE tries to avoid
254 * over-reads when calculating strlen(@q), it is still possible.
255 * Prefer strscpy(), though note its different return values for
256 * detecting truncation.
258 * Returns total number of bytes written to @p, including terminating NUL.
261 __FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, size_t size)
263 size_t p_size = __member_size(p);
264 size_t q_size = __member_size(q);
265 size_t q_len; /* Full count of source string length. */
266 size_t len; /* Count of characters going into destination. */
268 if (p_size == SIZE_MAX && q_size == SIZE_MAX)
269 return __real_strlcpy(p, q, size);
271 len = (q_len >= size) ? size - 1 : q_len;
272 if (__builtin_constant_p(size) && __builtin_constant_p(q_len) && size) {
273 /* Write size is always larger than destination. */
279 fortify_panic(__func__);
280 __underlying_memcpy(p, q, len);
286 /* Defined after fortified strnlen() to reuse it. */
287 extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy);
289 * strscpy - Copy a C-string into a sized buffer
291 * @p: Where to copy the string to
292 * @q: Where to copy the string from
293 * @size: Size of destination buffer
295 * Copy the source string @p, or as much of it as fits, into the destination
296 * @q buffer. The behavior is undefined if the string buffers overlap. The
297 * destination @p buffer is always NUL terminated, unless it's zero-sized.
299 * Preferred to strlcpy() since the API doesn't require reading memory
300 * from the source @q string beyond the specified @size bytes, and since
301 * the return value is easier to error-check than strlcpy()'s.
302 * In addition, the implementation is robust to the string changing out
303 * from underneath it, unlike the current strlcpy() implementation.
305 * Preferred to strncpy() since it always returns a valid string, and
306 * doesn't unnecessarily force the tail of the destination buffer to be
307 * zero padded. If padding is desired please use strscpy_pad().
309 * Returns the number of characters copied in @p (not including the
310 * trailing %NUL) or -E2BIG if @size is 0 or the copy of @q was truncated.
312 __FORTIFY_INLINE ssize_t strscpy(char * const POS p, const char * const POS q, size_t size)
315 /* Use string size rather than possible enclosing struct size. */
316 size_t p_size = __member_size(p);
317 size_t q_size = __member_size(q);
319 /* If we cannot get size of p and q default to call strscpy. */
320 if (p_size == SIZE_MAX && q_size == SIZE_MAX)
321 return __real_strscpy(p, q, size);
324 * If size can be known at compile time and is greater than
325 * p_size, generate a compile time write overflow error.
327 if (__compiletime_lessthan(p_size, size))
330 /* Short-circuit for compile-time known-safe lengths. */
331 if (__compiletime_lessthan(p_size, SIZE_MAX)) {
332 len = __compiletime_strlen(q);
334 if (len < SIZE_MAX && __compiletime_lessthan(len, size)) {
335 __underlying_memcpy(p, q, len + 1);
341 * This call protects from read overflow, because len will default to q
342 * length if it smaller than size.
344 len = strnlen(q, size);
346 * If len equals size, we will copy only size bytes which leads to
347 * -E2BIG being returned.
348 * Otherwise we will copy len + 1 because of the final '\O'.
350 len = len == size ? size : len + 1;
353 * Generate a runtime write overflow error if len is greater than
357 fortify_panic(__func__);
360 * We can now safely call vanilla strscpy because we are protected from:
361 * 1. Read overflow thanks to call to strnlen().
362 * 2. Write overflow thanks to above ifs.
364 return __real_strscpy(p, q, len);
368 * strncat - Append a string to an existing string
370 * @p: pointer to NUL-terminated string to append to
371 * @q: pointer to source string to append from
372 * @count: Maximum bytes to read from @q
374 * Appends at most @count bytes from @q (stopping at the first
375 * NUL byte) after the NUL-terminated string at @p. @p will be
378 * Do not use this function. While FORTIFY_SOURCE tries to avoid
379 * read and write overflows, this is only possible when the sizes
380 * of @p and @q are known to the compiler. Prefer building the
381 * string with formatting, via scnprintf() or similar.
386 /* Defined after fortified strlen() and strnlen() to reuse them. */
387 __FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3)
388 char *strncat(char * const POS p, const char * const POS q, __kernel_size_t count)
390 size_t p_len, copy_len;
391 size_t p_size = __member_size(p);
392 size_t q_size = __member_size(q);
394 if (p_size == SIZE_MAX && q_size == SIZE_MAX)
395 return __underlying_strncat(p, q, count);
397 copy_len = strnlen(q, count);
398 if (p_size < p_len + copy_len + 1)
399 fortify_panic(__func__);
400 __underlying_memcpy(p + p_len, q, copy_len);
401 p[p_len + copy_len] = '\0';
405 __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size,
407 const size_t p_size_field)
409 if (__builtin_constant_p(size)) {
411 * Length argument is a constant expression, so we
412 * can perform compile-time bounds checking where
413 * buffer sizes are also known at compile time.
416 /* Error when size is larger than enclosing struct. */
417 if (__compiletime_lessthan(p_size_field, p_size) &&
418 __compiletime_lessthan(p_size, size))
421 /* Warn when write size is larger than dest field. */
422 if (__compiletime_lessthan(p_size_field, size))
423 __write_overflow_field(p_size_field, size);
426 * At this point, length argument may not be a constant expression,
427 * so run-time bounds checking can be done where buffer sizes are
428 * known. (This is not an "else" because the above checks may only
429 * be compile-time warnings, and we want to still warn for run-time
434 * Always stop accesses beyond the struct that contains the
435 * field, when the buffer's remaining size is known.
436 * (The SIZE_MAX test is to optimize away checks where the buffer
437 * lengths are unknown.)
439 if (p_size != SIZE_MAX && p_size < size)
440 fortify_panic("memset");
443 #define __fortify_memset_chk(p, c, size, p_size, p_size_field) ({ \
444 size_t __fortify_size = (size_t)(size); \
445 fortify_memset_chk(__fortify_size, p_size, p_size_field), \
446 __underlying_memset(p, c, __fortify_size); \
450 * __struct_size() vs __member_size() must be captured here to avoid
451 * evaluating argument side-effects further into the macro layers.
454 #define memset(p, c, s) __fortify_memset_chk(p, c, s, \
455 __struct_size(p), __member_size(p))
459 * To make sure the compiler can enforce protection against buffer overflows,
460 * memcpy(), memmove(), and memset() must not be used beyond individual
461 * struct members. If you need to copy across multiple members, please use
462 * struct_group() to create a named mirror of an anonymous struct union.
463 * (e.g. see struct sk_buff.) Read overflow checking is currently only
464 * done when a write overflow is also present, or when building with W=1.
466 * Mitigation coverage matrix
467 * Bounds checking at:
468 * +-------+-------+-------+-------+
469 * | Compile time | Run time |
470 * memcpy() argument sizes: | write | read | write | read |
471 * dest source length +-------+-------+-------+-------+
472 * memcpy(known, known, constant) | y | y | n/a | n/a |
473 * memcpy(known, unknown, constant) | y | n | n/a | V |
474 * memcpy(known, known, dynamic) | n | n | B | B |
475 * memcpy(known, unknown, dynamic) | n | n | B | V |
476 * memcpy(unknown, known, constant) | n | y | V | n/a |
477 * memcpy(unknown, unknown, constant) | n | n | V | V |
478 * memcpy(unknown, known, dynamic) | n | n | V | B |
479 * memcpy(unknown, unknown, dynamic) | n | n | V | V |
480 * +-------+-------+-------+-------+
482 * y = perform deterministic compile-time bounds checking
483 * n = cannot perform deterministic compile-time bounds checking
484 * n/a = no run-time bounds checking needed since compile-time deterministic
485 * B = can perform run-time bounds checking (currently unimplemented)
486 * V = vulnerable to run-time overflow (will need refactoring to solve)
489 __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
492 const size_t p_size_field,
493 const size_t q_size_field,
496 if (__builtin_constant_p(size)) {
498 * Length argument is a constant expression, so we
499 * can perform compile-time bounds checking where
500 * buffer sizes are also known at compile time.
503 /* Error when size is larger than enclosing struct. */
504 if (__compiletime_lessthan(p_size_field, p_size) &&
505 __compiletime_lessthan(p_size, size))
507 if (__compiletime_lessthan(q_size_field, q_size) &&
508 __compiletime_lessthan(q_size, size))
511 /* Warn when write size argument larger than dest field. */
512 if (__compiletime_lessthan(p_size_field, size))
513 __write_overflow_field(p_size_field, size);
515 * Warn for source field over-read when building with W=1
516 * or when an over-write happened, so both can be fixed at
519 if ((IS_ENABLED(KBUILD_EXTRA_WARN1) ||
520 __compiletime_lessthan(p_size_field, size)) &&
521 __compiletime_lessthan(q_size_field, size))
522 __read_overflow2_field(q_size_field, size);
525 * At this point, length argument may not be a constant expression,
526 * so run-time bounds checking can be done where buffer sizes are
527 * known. (This is not an "else" because the above checks may only
528 * be compile-time warnings, and we want to still warn for run-time
533 * Always stop accesses beyond the struct that contains the
534 * field, when the buffer's remaining size is known.
535 * (The SIZE_MAX test is to optimize away checks where the buffer
536 * lengths are unknown.)
538 if ((p_size != SIZE_MAX && p_size < size) ||
539 (q_size != SIZE_MAX && q_size < size))
543 * Warn when writing beyond destination field size.
545 * We must ignore p_size_field == 0 for existing 0-element
546 * fake flexible arrays, until they are all converted to
547 * proper flexible arrays.
549 * The implementation of __builtin_*object_size() behaves
550 * like sizeof() when not directly referencing a flexible
551 * array member, which means there will be many bounds checks
552 * that will appear at run-time, without a way for them to be
553 * detected at compile-time (as can be done when the destination
554 * is specifically the flexible array member).
555 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832
557 if (p_size_field != 0 && p_size_field != SIZE_MAX &&
558 p_size != p_size_field && p_size_field < size)
564 #define __fortify_memcpy_chk(p, q, size, p_size, q_size, \
565 p_size_field, q_size_field, op) ({ \
566 const size_t __fortify_size = (size_t)(size); \
567 const size_t __p_size = (p_size); \
568 const size_t __q_size = (q_size); \
569 const size_t __p_size_field = (p_size_field); \
570 const size_t __q_size_field = (q_size_field); \
571 WARN_ONCE(fortify_memcpy_chk(__fortify_size, __p_size, \
572 __q_size, __p_size_field, \
573 __q_size_field, #op), \
574 #op ": detected field-spanning write (size %zu) of single %s (size %zu)\n", \
576 "field \"" #p "\" at " __FILE__ ":" __stringify(__LINE__), \
578 __underlying_##op(p, q, __fortify_size); \
582 * Notes about compile-time buffer size detection:
584 * With these types...
600 * void func(TYPE *ptr) { ... }
602 * Cases where destination size cannot be currently detected:
603 * - the size of ptr's object (seemingly by design, gcc & clang fail):
604 * __builtin_object_size(ptr, 1) == SIZE_MAX
605 * - the size of flexible arrays in ptr's obj (by design, dynamic size):
606 * __builtin_object_size(ptr->flex_buf, 1) == SIZE_MAX
607 * - the size of ANY array at the end of ptr's obj (gcc and clang bug):
608 * __builtin_object_size(ptr->end_buf, 1) == SIZE_MAX
609 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836
611 * Cases where destination size is currently detected:
612 * - the size of non-array members within ptr's object:
613 * __builtin_object_size(ptr->a, 1) == 2
614 * - the size of non-flexible-array in the middle of ptr's obj:
615 * __builtin_object_size(ptr->middle_buf, 1) == 16
620 * __struct_size() vs __member_size() must be captured here to avoid
621 * evaluating argument side-effects further into the macro layers.
623 #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \
624 __struct_size(p), __struct_size(q), \
625 __member_size(p), __member_size(q), \
627 #define memmove(p, q, s) __fortify_memcpy_chk(p, q, s, \
628 __struct_size(p), __struct_size(q), \
629 __member_size(p), __member_size(q), \
632 extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan);
633 __FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size)
635 size_t p_size = __struct_size(p);
637 if (__compiletime_lessthan(p_size, size))
640 fortify_panic(__func__);
641 return __real_memscan(p, c, size);
644 __FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3)
645 int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t size)
647 size_t p_size = __struct_size(p);
648 size_t q_size = __struct_size(q);
650 if (__builtin_constant_p(size)) {
651 if (__compiletime_lessthan(p_size, size))
653 if (__compiletime_lessthan(q_size, size))
656 if (p_size < size || q_size < size)
657 fortify_panic(__func__);
658 return __underlying_memcmp(p, q, size);
661 __FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3)
662 void *memchr(const void * const POS0 p, int c, __kernel_size_t size)
664 size_t p_size = __struct_size(p);
666 if (__compiletime_lessthan(p_size, size))
669 fortify_panic(__func__);
670 return __underlying_memchr(p, c, size);
673 void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv);
674 __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size)
676 size_t p_size = __struct_size(p);
678 if (__compiletime_lessthan(p_size, size))
681 fortify_panic(__func__);
682 return __real_memchr_inv(p, c, size);
685 extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup)
687 __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp)
689 size_t p_size = __struct_size(p);
691 if (__compiletime_lessthan(p_size, size))
694 fortify_panic(__func__);
695 return __real_kmemdup(p, size, gfp);
699 * strcpy - Copy a string into another string buffer
701 * @p: pointer to destination of copy
702 * @q: pointer to NUL-terminated source string to copy
704 * Do not use this function. While FORTIFY_SOURCE tries to avoid
705 * overflows, this is only possible when the sizes of @q and @p are
706 * known to the compiler. Prefer strscpy(), though note its different
707 * return values for detecting truncation.
712 /* Defined after fortified strlen to reuse it. */
713 __FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2)
714 char *strcpy(char * const POS p, const char * const POS q)
716 size_t p_size = __member_size(p);
717 size_t q_size = __member_size(q);
720 /* If neither buffer size is known, immediately give up. */
721 if (__builtin_constant_p(p_size) &&
722 __builtin_constant_p(q_size) &&
723 p_size == SIZE_MAX && q_size == SIZE_MAX)
724 return __underlying_strcpy(p, q);
725 size = strlen(q) + 1;
726 /* Compile-time check for const size overflow. */
727 if (__compiletime_lessthan(p_size, size))
729 /* Run-time check for dynamic size overflow. */
731 fortify_panic(__func__);
732 __underlying_memcpy(p, q, size);
736 /* Don't use these outside the FORITFY_SOURCE implementation */
737 #undef __underlying_memchr
738 #undef __underlying_memcmp
739 #undef __underlying_strcat
740 #undef __underlying_strcpy
741 #undef __underlying_strlen
742 #undef __underlying_strncat
743 #undef __underlying_strncpy
748 #endif /* _LINUX_FORTIFY_STRING_H_ */