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편집 파일: fortify-string.h

/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_FORTIFY_STRING_H_ #define _LINUX_FORTIFY_STRING_H_ #include <linux/bug.h> #include <linux/const.h> #include <linux/limits.h> #define __FORTIFY_INLINE extern __always_inline __gnu_inline __overloadable #define __RENAME(x) __asm__(#x) void fortify_panic(const char *name) __noreturn __cold; void __read_overflow(void) __compiletime_error("detected read beyond size of object (1st parameter)"); void __read_overflow2(void) __compiletime_error("detected read beyond size of object (2nd parameter)"); void __read_overflow2_field(size_t avail, size_t wanted) __compiletime_warning("detected read beyond size of field (2nd parameter); maybe use struct_group()?"); void __write_overflow(void) __compiletime_error("detected write beyond size of object (1st parameter)"); void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("detected write beyond size of field (1st parameter); maybe use struct_group()?"); #define __compiletime_strlen(p) \ ({ \ unsigned char *__p = (unsigned char *)(p); \ size_t __ret = SIZE_MAX; \ const size_t __p_size = __member_size(p); \ if (__p_size != SIZE_MAX && \ __builtin_constant_p(*__p)) { \ size_t __p_len = __p_size - 1; \ if (__builtin_constant_p(__p[__p_len]) && \ __p[__p_len] == '\0') \ __ret = __builtin_strlen(__p); \ } \ __ret; \ }) #if defined(__SANITIZE_ADDRESS__) #if !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX) && !defined(CONFIG_GENERIC_ENTRY) extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset); extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove); extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy); #elif defined(CONFIG_KASAN_GENERIC) extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__asan_memset); extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memmove); extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memcpy); #else /* CONFIG_KASAN_SW_TAGS */ extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__hwasan_memset); extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memmove); extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memcpy); #endif extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr); extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp); extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat); extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy); extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen); extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat); extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy); #else #if defined(__SANITIZE_MEMORY__) /* * For KMSAN builds all memcpy/memset/memmove calls should be replaced by the * corresponding __msan_XXX functions. */ #include <linux/kmsan_string.h> #define __underlying_memcpy __msan_memcpy #define __underlying_memmove __msan_memmove #define __underlying_memset __msan_memset #else #define __underlying_memcpy __builtin_memcpy #define __underlying_memmove __builtin_memmove #define __underlying_memset __builtin_memset #endif #define __underlying_memchr __builtin_memchr #define __underlying_memcmp __builtin_memcmp #define __underlying_strcat __builtin_strcat #define __underlying_strcpy __builtin_strcpy #define __underlying_strlen __builtin_strlen #define __underlying_strncat __builtin_strncat #define __underlying_strncpy __builtin_strncpy #endif /** * unsafe_memcpy - memcpy implementation with no FORTIFY bounds checking * * @dst: Destination memory address to write to * @src: Source memory address to read from * @bytes: How many bytes to write to @dst from @src * @justification: Free-form text or comment describing why the use is needed * * This should be used for corner cases where the compiler cannot do the * right thing, or during transitions between APIs, etc. It should be used * very rarely, and includes a place for justification detailing where bounds * checking has happened, and why existing solutions cannot be employed. */ #define unsafe_memcpy(dst, src, bytes, justification) \ __underlying_memcpy(dst, src, bytes) /* * Clang's use of __builtin_*object_size() within inlines needs hinting via * __pass_*object_size(). The preference is to only ever use type 1 (member * size, rather than struct size), but there remain some stragglers using * type 0 that will be converted in the future. */ #if __has_builtin(__builtin_dynamic_object_size) #define POS __pass_dynamic_object_size(1) #define POS0 __pass_dynamic_object_size(0) #else #define POS __pass_object_size(1) #define POS0 __pass_object_size(0) #endif #define __compiletime_lessthan(bounds, length) ( \ __builtin_constant_p((bounds) < (length)) && \ (bounds) < (length) \ ) /** * strncpy - Copy a string to memory with non-guaranteed NUL padding * * @p: pointer to destination of copy * @q: pointer to NUL-terminated source string to copy * @size: bytes to write at @p * * If strlen(@q) >= @size, the copy of @q will stop after @size bytes, * and @p will NOT be NUL-terminated * * If strlen(@q) < @size, following the copy of @q, trailing NUL bytes * will be written to @p until @size total bytes have been written. * * Do not use this function. While FORTIFY_SOURCE tries to avoid * over-reads of @q, it cannot defend against writing unterminated * results to @p. Using strncpy() remains ambiguous and fragile. * Instead, please choose an alternative, so that the expectation * of @p's contents is unambiguous: * * +--------------------+--------------------+------------+ * | **p** needs to be: | padded to **size** | not padded | * +====================+====================+============+ * | NUL-terminated | strscpy_pad() | strscpy() | * +--------------------+--------------------+------------+ * | not NUL-terminated | strtomem_pad() | strtomem() | * +--------------------+--------------------+------------+ * * Note strscpy*()'s differing return values for detecting truncation, * and strtomem*()'s expectation that the destination is marked with * __nonstring when it is a character array. * */ __FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3) char *strncpy(char * const POS p, const char *q, __kernel_size_t size) { const size_t p_size = __member_size(p); if (__compiletime_lessthan(p_size, size)) __write_overflow(); if (p_size < size) fortify_panic(__func__); return __underlying_strncpy(p, q, size); } /** * strcat - Append a string to an existing string * * @p: pointer to NUL-terminated string to append to * @q: pointer to NUL-terminated source string to append from * * Do not use this function. While FORTIFY_SOURCE tries to avoid * read and write overflows, this is only possible when the * destination buffer size is known to the compiler. Prefer * building the string with formatting, via scnprintf() or similar. * At the very least, use strncat(). * * Returns @p. * */ __FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2) char *strcat(char * const POS p, const char *q) { const size_t p_size = __member_size(p); if (p_size == SIZE_MAX) return __underlying_strcat(p, q); if (strlcat(p, q, p_size) >= p_size) fortify_panic(__func__); return p; } extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen); /** * strnlen - Return bounded count of characters in a NUL-terminated string * * @p: pointer to NUL-terminated string to count. * @maxlen: maximum number of characters to count. * * Returns number of characters in @p (NOT including the final NUL), or * @maxlen, if no NUL has been found up to there. * */ __FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size_t maxlen) { const size_t p_size = __member_size(p); const size_t p_len = __compiletime_strlen(p); size_t ret; /* We can take compile-time actions when maxlen is const. */ if (__builtin_constant_p(maxlen) && p_len != SIZE_MAX) { /* If p is const, we can use its compile-time-known len. */ if (maxlen >= p_size) return p_len; } /* Do not check characters beyond the end of p. */ ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size); if (p_size <= ret && maxlen != ret) fortify_panic(__func__); return ret; } /* * Defined after fortified strnlen to reuse it. However, it must still be * possible for strlen() to be used on compile-time strings for use in * static initializers (i.e. as a constant expression). */ /** * strlen - Return count of characters in a NUL-terminated string * * @p: pointer to NUL-terminated string to count. * * Do not use this function unless the string length is known at * compile-time. When @p is unterminated, this function may crash * or return unexpected counts that could lead to memory content * exposures. Prefer strnlen(). * * Returns number of characters in @p (NOT including the final NUL). * */ #define strlen(p) \ __builtin_choose_expr(__is_constexpr(__builtin_strlen(p)), \ __builtin_strlen(p), __fortify_strlen(p)) __FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1) __kernel_size_t __fortify_strlen(const char * const POS p) { const size_t p_size = __member_size(p); __kernel_size_t ret; /* Give up if we don't know how large p is. */ if (p_size == SIZE_MAX) return __underlying_strlen(p); ret = strnlen(p, p_size); if (p_size <= ret) fortify_panic(__func__); return ret; } /* Defined after fortified strlen() to reuse it. */ extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy); /** * strlcpy - Copy a string into another string buffer * * @p: pointer to destination of copy * @q: pointer to NUL-terminated source string to copy * @size: maximum number of bytes to write at @p * * If strlen(@q) >= @size, the copy of @q will be truncated at * @size - 1 bytes. @p will always be NUL-terminated. * * Do not use this function. While FORTIFY_SOURCE tries to avoid * over-reads when calculating strlen(@q), it is still possible. * Prefer strscpy(), though note its different return values for * detecting truncation. * * Returns total number of bytes written to @p, including terminating NUL. * */ __FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, size_t size) { const size_t p_size = __member_size(p); const size_t q_size = __member_size(q); size_t q_len; /* Full count of source string length. */ size_t len; /* Count of characters going into destination. */ if (p_size == SIZE_MAX && q_size == SIZE_MAX) return __real_strlcpy(p, q, size); q_len = strlen(q); len = (q_len >= size) ? size - 1 : q_len; if (__builtin_constant_p(size) && __builtin_constant_p(q_len) && size) { /* Write size is always larger than destination. */ if (len >= p_size) __write_overflow(); } if (size) { if (len >= p_size) fortify_panic(__func__); __underlying_memcpy(p, q, len); p[len] = '\0'; } return q_len; } /* Defined after fortified strnlen() to reuse it. */ extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(sized_strscpy); __FORTIFY_INLINE ssize_t sized_strscpy(char * const POS p, const char * const POS q, size_t size) { /* Use string size rather than possible enclosing struct size. */ const size_t p_size = __member_size(p); const size_t q_size = __member_size(q); size_t len; /* If we cannot get size of p and q default to call strscpy. */ if (p_size == SIZE_MAX && q_size == SIZE_MAX) return __real_strscpy(p, q, size); /* * If size can be known at compile time and is greater than * p_size, generate a compile time write overflow error. */ if (__compiletime_lessthan(p_size, size)) __write_overflow(); /* Short-circuit for compile-time known-safe lengths. */ if (__compiletime_lessthan(p_size, SIZE_MAX)) { len = __compiletime_strlen(q); if (len < SIZE_MAX && __compiletime_lessthan(len, size)) { __underlying_memcpy(p, q, len + 1); return len; } } /* * This call protects from read overflow, because len will default to q * length if it smaller than size. */ len = strnlen(q, size); /* * If len equals size, we will copy only size bytes which leads to * -E2BIG being returned. * Otherwise we will copy len + 1 because of the final '\O'. */ len = len == size ? size : len + 1; /* * Generate a runtime write overflow error if len is greater than * p_size. */ if (len > p_size) fortify_panic(__func__); /* * We can now safely call vanilla strscpy because we are protected from: * 1. Read overflow thanks to call to strnlen(). * 2. Write overflow thanks to above ifs. */ return __real_strscpy(p, q, len); } /** * strncat - Append a string to an existing string * * @p: pointer to NUL-terminated string to append to * @q: pointer to source string to append from * @count: Maximum bytes to read from @q * * Appends at most @count bytes from @q (stopping at the first * NUL byte) after the NUL-terminated string at @p. @p will be * NUL-terminated. * * Do not use this function. While FORTIFY_SOURCE tries to avoid * read and write overflows, this is only possible when the sizes * of @p and @q are known to the compiler. Prefer building the * string with formatting, via scnprintf() or similar. * * Returns @p. * */ /* Defined after fortified strlen() and strnlen() to reuse them. */ __FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3) char *strncat(char * const POS p, const char * const POS q, __kernel_size_t count) { const size_t p_size = __member_size(p); const size_t q_size = __member_size(q); size_t p_len, copy_len; if (p_size == SIZE_MAX && q_size == SIZE_MAX) return __underlying_strncat(p, q, count); p_len = strlen(p); copy_len = strnlen(q, count); if (p_size < p_len + copy_len + 1) fortify_panic(__func__); __underlying_memcpy(p + p_len, q, copy_len); p[p_len + copy_len] = '\0'; return p; } __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size, const size_t p_size, const size_t p_size_field) { if (__builtin_constant_p(size)) { /* * Length argument is a constant expression, so we * can perform compile-time bounds checking where * buffer sizes are also known at compile time. */ /* Error when size is larger than enclosing struct. */ if (__compiletime_lessthan(p_size_field, p_size) && __compiletime_lessthan(p_size, size)) __write_overflow(); /* Warn when write size is larger than dest field. */ if (__compiletime_lessthan(p_size_field, size)) __write_overflow_field(p_size_field, size); } /* * At this point, length argument may not be a constant expression, * so run-time bounds checking can be done where buffer sizes are * known. (This is not an "else" because the above checks may only * be compile-time warnings, and we want to still warn for run-time * overflows.) */ /* * Always stop accesses beyond the struct that contains the * field, when the buffer's remaining size is known. * (The SIZE_MAX test is to optimize away checks where the buffer * lengths are unknown.) */ if (p_size != SIZE_MAX && p_size < size) fortify_panic("memset"); } #define __fortify_memset_chk(p, c, size, p_size, p_size_field) ({ \ size_t __fortify_size = (size_t)(size); \ fortify_memset_chk(__fortify_size, p_size, p_size_field), \ __underlying_memset(p, c, __fortify_size); \ }) /* * __struct_size() vs __member_size() must be captured here to avoid * evaluating argument side-effects further into the macro layers. */ #ifndef CONFIG_KMSAN #define memset(p, c, s) __fortify_memset_chk(p, c, s, \ __struct_size(p), __member_size(p)) #endif /* * To make sure the compiler can enforce protection against buffer overflows, * memcpy(), memmove(), and memset() must not be used beyond individual * struct members. If you need to copy across multiple members, please use * struct_group() to create a named mirror of an anonymous struct union. * (e.g. see struct sk_buff.) Read overflow checking is currently only * done when a write overflow is also present, or when building with W=1. * * Mitigation coverage matrix * Bounds checking at: * +-------+-------+-------+-------+ * | Compile time | Run time | * memcpy() argument sizes: | write | read | write | read | * dest source length +-------+-------+-------+-------+ * memcpy(known, known, constant) | y | y | n/a | n/a | * memcpy(known, unknown, constant) | y | n | n/a | V | * memcpy(known, known, dynamic) | n | n | B | B | * memcpy(known, unknown, dynamic) | n | n | B | V | * memcpy(unknown, known, constant) | n | y | V | n/a | * memcpy(unknown, unknown, constant) | n | n | V | V | * memcpy(unknown, known, dynamic) | n | n | V | B | * memcpy(unknown, unknown, dynamic) | n | n | V | V | * +-------+-------+-------+-------+ * * y = perform deterministic compile-time bounds checking * n = cannot perform deterministic compile-time bounds checking * n/a = no run-time bounds checking needed since compile-time deterministic * B = can perform run-time bounds checking (currently unimplemented) * V = vulnerable to run-time overflow (will need refactoring to solve) * */ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size, const size_t p_size, const size_t q_size, const size_t p_size_field, const size_t q_size_field, const char *func) { if (__builtin_constant_p(size)) { /* * Length argument is a constant expression, so we * can perform compile-time bounds checking where * buffer sizes are also known at compile time. */ /* Error when size is larger than enclosing struct. */ if (__compiletime_lessthan(p_size_field, p_size) && __compiletime_lessthan(p_size, size)) __write_overflow(); if (__compiletime_lessthan(q_size_field, q_size) && __compiletime_lessthan(q_size, size)) __read_overflow2(); /* Warn when write size argument larger than dest field. */ if (__compiletime_lessthan(p_size_field, size)) __write_overflow_field(p_size_field, size); /* * Warn for source field over-read when building with W=1 * or when an over-write happened, so both can be fixed at * the same time. */ if ((IS_ENABLED(KBUILD_EXTRA_WARN1) || __compiletime_lessthan(p_size_field, size)) && __compiletime_lessthan(q_size_field, size)) __read_overflow2_field(q_size_field, size); } /* * At this point, length argument may not be a constant expression, * so run-time bounds checking can be done where buffer sizes are * known. (This is not an "else" because the above checks may only * be compile-time warnings, and we want to still warn for run-time * overflows.) */ /* * Always stop accesses beyond the struct that contains the * field, when the buffer's remaining size is known. * (The SIZE_MAX test is to optimize away checks where the buffer * lengths are unknown.) */ if ((p_size != SIZE_MAX && p_size < size) || (q_size != SIZE_MAX && q_size < size)) fortify_panic(func); /* * Warn when writing beyond destination field size. * * We must ignore p_size_field == 0 for existing 0-element * fake flexible arrays, until they are all converted to * proper flexible arrays. * * The implementation of __builtin_*object_size() behaves * like sizeof() when not directly referencing a flexible * array member, which means there will be many bounds checks * that will appear at run-time, without a way for them to be * detected at compile-time (as can be done when the destination * is specifically the flexible array member). * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832 */ if (p_size_field != 0 && p_size_field != SIZE_MAX && p_size != p_size_field && p_size_field < size) return true; return false; } #define __fortify_memcpy_chk(p, q, size, p_size, q_size, \ p_size_field, q_size_field, op) ({ \ size_t __fortify_size = (size_t)(size); \ WARN_ONCE(fortify_memcpy_chk(__fortify_size, p_size, q_size, \ p_size_field, q_size_field, #op), \ #op ": detected field-spanning write (size %zu) of single %s (size %zu)\n", \ __fortify_size, \ "field \"" #p "\" at " __FILE__ ":" __stringify(__LINE__), \ p_size_field); \ __underlying_##op(p, q, __fortify_size); \ }) /* * Notes about compile-time buffer size detection: * * With these types... * * struct middle { * u16 a; * u8 middle_buf[16]; * int b; * }; * struct end { * u16 a; * u8 end_buf[16]; * }; * struct flex { * int a; * u8 flex_buf[]; * }; * * void func(TYPE *ptr) { ... } * * Cases where destination size cannot be currently detected: * - the size of ptr's object (seemingly by design, gcc & clang fail): * __builtin_object_size(ptr, 1) == SIZE_MAX * - the size of flexible arrays in ptr's obj (by design, dynamic size): * __builtin_object_size(ptr->flex_buf, 1) == SIZE_MAX * - the size of ANY array at the end of ptr's obj (gcc and clang bug): * __builtin_object_size(ptr->end_buf, 1) == SIZE_MAX * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 * * Cases where destination size is currently detected: * - the size of non-array members within ptr's object: * __builtin_object_size(ptr->a, 1) == 2 * - the size of non-flexible-array in the middle of ptr's obj: * __builtin_object_size(ptr->middle_buf, 1) == 16 * */ /* * __struct_size() vs __member_size() must be captured here to avoid * evaluating argument side-effects further into the macro layers. */ #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ __struct_size(p), __struct_size(q), \ __member_size(p), __member_size(q), \ memcpy) #define memmove(p, q, s) __fortify_memcpy_chk(p, q, s, \ __struct_size(p), __struct_size(q), \ __member_size(p), __member_size(q), \ memmove) extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan); __FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size) { const size_t p_size = __struct_size(p); if (__compiletime_lessthan(p_size, size)) __read_overflow(); if (p_size < size) fortify_panic(__func__); return __real_memscan(p, c, size); } __FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3) int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t size) { const size_t p_size = __struct_size(p); const size_t q_size = __struct_size(q); if (__builtin_constant_p(size)) { if (__compiletime_lessthan(p_size, size)) __read_overflow(); if (__compiletime_lessthan(q_size, size)) __read_overflow2(); } if (p_size < size || q_size < size) fortify_panic(__func__); return __underlying_memcmp(p, q, size); } __FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3) void *memchr(const void * const POS0 p, int c, __kernel_size_t size) { const size_t p_size = __struct_size(p); if (__compiletime_lessthan(p_size, size)) __read_overflow(); if (p_size < size) fortify_panic(__func__); return __underlying_memchr(p, c, size); } void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv); __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size) { const size_t p_size = __struct_size(p); if (__compiletime_lessthan(p_size, size)) __read_overflow(); if (p_size < size) fortify_panic(__func__); return __real_memchr_inv(p, c, size); } extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup) __realloc_size(2); __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp) { const size_t p_size = __struct_size(p); if (__compiletime_lessthan(p_size, size)) __read_overflow(); if (p_size < size) fortify_panic(__func__); return __real_kmemdup(p, size, gfp); } /** * strcpy - Copy a string into another string buffer * * @p: pointer to destination of copy * @q: pointer to NUL-terminated source string to copy * * Do not use this function. While FORTIFY_SOURCE tries to avoid * overflows, this is only possible when the sizes of @q and @p are * known to the compiler. Prefer strscpy(), though note its different * return values for detecting truncation. * * Returns @p. * */ /* Defined after fortified strlen to reuse it. */ __FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2) char *strcpy(char * const POS p, const char * const POS q) { const size_t p_size = __member_size(p); const size_t q_size = __member_size(q); size_t size; /* If neither buffer size is known, immediately give up. */ if (__builtin_constant_p(p_size) && __builtin_constant_p(q_size) && p_size == SIZE_MAX && q_size == SIZE_MAX) return __underlying_strcpy(p, q); size = strlen(q) + 1; /* Compile-time check for const size overflow. */ if (__compiletime_lessthan(p_size, size)) __write_overflow(); /* Run-time check for dynamic size overflow. */ if (p_size < size) fortify_panic(__func__); __underlying_memcpy(p, q, size); return p; } /* Don't use these outside the FORITFY_SOURCE implementation */ #undef __underlying_memchr #undef __underlying_memcmp #undef __underlying_strcat #undef __underlying_strcpy #undef __underlying_strlen #undef __underlying_strncat #undef __underlying_strncpy #undef POS #undef POS0 #endif /* _LINUX_FORTIFY_STRING_H_ */