diff options
Diffstat (limited to 'include/linux/fortify-string.h')
| -rw-r--r-- | include/linux/fortify-string.h | 405 |
1 files changed, 330 insertions, 75 deletions
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h index 3b401fa0f374..7cad8bb031e9 100644 --- a/include/linux/fortify-string.h +++ b/include/linux/fortify-string.h @@ -2,7 +2,9 @@ #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) @@ -16,10 +18,11 @@ void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning(" #define __compiletime_strlen(p) \ ({ \ - unsigned char *__p = (unsigned char *)(p); \ - size_t __ret = (size_t)-1; \ - size_t __p_size = __builtin_object_size(p, 1); \ - if (__p_size != (size_t)-1) { \ + char *__p = (char *)(p); \ + size_t __ret = SIZE_MAX; \ + 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') \ @@ -40,11 +43,24 @@ 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 -#define __underlying_memchr __builtin_memchr -#define __underlying_memcmp __builtin_memcmp + +#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 @@ -69,32 +85,86 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __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 + * 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. */ -#define POS __pass_object_size(1) -#define POS0 __pass_object_size(0) +#define POS __pass_object_size(1) +#define POS0 __pass_object_size(0) +#define __struct_size(p) __builtin_object_size(p, 0) +#define __member_size(p) __builtin_object_size(p, 1) + +#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) { - size_t p_size = __builtin_object_size(p, 1); + size_t p_size = __member_size(p); - if (__builtin_constant_p(size) && p_size < size) + 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) { - size_t p_size = __builtin_object_size(p, 1); + size_t p_size = __member_size(p); - if (p_size == (size_t)-1) + if (p_size == SIZE_MAX) return __underlying_strcat(p, q); if (strlcat(p, q, p_size) >= p_size) fortify_panic(__func__); @@ -102,14 +172,24 @@ char *strcat(char * const POS p, const char *q) } 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) { - size_t p_size = __builtin_object_size(p, 1); + size_t p_size = __member_size(p); 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_t)-1) { + 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; @@ -127,6 +207,19 @@ __FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size * 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)) @@ -134,10 +227,10 @@ __FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1) __kernel_size_t __fortify_strlen(const char * const POS p) { __kernel_size_t ret; - size_t p_size = __builtin_object_size(p, 1); + size_t p_size = __member_size(p); /* Give up if we don't know how large p is. */ - if (p_size == (size_t)-1) + if (p_size == SIZE_MAX) return __underlying_strlen(p); ret = strnlen(p, p_size); if (p_size <= ret) @@ -145,16 +238,34 @@ __kernel_size_t __fortify_strlen(const char * const POS p) return ret; } -/* defined after fortified strlen to reuse it */ +/* 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) { - size_t p_size = __builtin_object_size(p, 1); - size_t q_size = __builtin_object_size(q, 1); + size_t p_size = __member_size(p); + 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_t)-1 && q_size == (size_t)-1) + 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; @@ -172,26 +283,60 @@ __FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, si return q_len; } -/* defined after fortified strnlen to reuse it */ +/* Defined after fortified strnlen() to reuse it. */ extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy); +/** + * strscpy - Copy a C-string into a sized buffer + * + * @p: Where to copy the string to + * @q: Where to copy the string from + * @size: Size of destination buffer + * + * Copy the source string @p, or as much of it as fits, into the destination + * @q buffer. The behavior is undefined if the string buffers overlap. The + * destination @p buffer is always NUL terminated, unless it's zero-sized. + * + * Preferred to strlcpy() since the API doesn't require reading memory + * from the source @q string beyond the specified @size bytes, and since + * the return value is easier to error-check than strlcpy()'s. + * In addition, the implementation is robust to the string changing out + * from underneath it, unlike the current strlcpy() implementation. + * + * Preferred to strncpy() since it always returns a valid string, and + * doesn't unnecessarily force the tail of the destination buffer to be + * zero padded. If padding is desired please use strscpy_pad(). + * + * Returns the number of characters copied in @p (not including the + * trailing %NUL) or -E2BIG if @size is 0 or the copy of @q was truncated. + */ __FORTIFY_INLINE ssize_t strscpy(char * const POS p, const char * const POS q, size_t size) { size_t len; /* Use string size rather than possible enclosing struct size. */ - size_t p_size = __builtin_object_size(p, 1); - size_t q_size = __builtin_object_size(q, 1); + size_t p_size = __member_size(p); + size_t q_size = __member_size(q); /* If we cannot get size of p and q default to call strscpy. */ - if (p_size == (size_t) -1 && q_size == (size_t) -1) + 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 (__builtin_constant_p(size) && size > p_size) + 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. @@ -219,15 +364,34 @@ __FORTIFY_INLINE ssize_t strscpy(char * const POS p, const char * const POS q, s return __real_strscpy(p, q, len); } -/* defined after fortified strlen and strnlen to reuse them */ +/** + * 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) { size_t p_len, copy_len; - size_t p_size = __builtin_object_size(p, 1); - size_t q_size = __builtin_object_size(q, 1); + size_t p_size = __member_size(p); + size_t q_size = __member_size(q); - if (p_size == (size_t)-1 && q_size == (size_t)-1) + if (p_size == SIZE_MAX && q_size == SIZE_MAX) return __underlying_strncat(p, q, count); p_len = strlen(p); copy_len = strnlen(q, count); @@ -246,15 +410,16 @@ __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size, /* * Length argument is a constant expression, so we * can perform compile-time bounds checking where - * buffer sizes are known. + * buffer sizes are also known at compile time. */ /* Error when size is larger than enclosing struct. */ - if (p_size > p_size_field && p_size < size) + 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 (p_size_field < size) + if (__compiletime_lessthan(p_size_field, size)) __write_overflow_field(p_size_field, size); } /* @@ -268,10 +433,10 @@ __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size, /* * Always stop accesses beyond the struct that contains the * field, when the buffer's remaining size is known. - * (The -1 test is to optimize away checks where the buffer + * (The SIZE_MAX test is to optimize away checks where the buffer * lengths are unknown.) */ - if (p_size != (size_t)(-1) && p_size < size) + if (p_size != SIZE_MAX && p_size < size) fortify_panic("memset"); } @@ -282,11 +447,13 @@ __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size, }) /* - * __builtin_object_size() must be captured here to avoid evaluating argument - * side-effects further into the macro layers. + * __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, \ - __builtin_object_size(p, 0), __builtin_object_size(p, 1)) + __struct_size(p), __member_size(p)) +#endif /* * To make sure the compiler can enforce protection against buffer overflows, @@ -319,7 +486,7 @@ __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size, * V = vulnerable to run-time overflow (will need refactoring to solve) * */ -__FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size, +__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, @@ -330,25 +497,28 @@ __FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size, /* * Length argument is a constant expression, so we * can perform compile-time bounds checking where - * buffer sizes are known. + * buffer sizes are also known at compile time. */ /* Error when size is larger than enclosing struct. */ - if (p_size > p_size_field && p_size < size) + if (__compiletime_lessthan(p_size_field, p_size) && + __compiletime_lessthan(p_size, size)) __write_overflow(); - if (q_size > q_size_field && q_size < size) + 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 (p_size_field < size) + 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) || p_size_field < size) && - q_size_field < size) + 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); } /* @@ -362,41 +532,109 @@ __FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size, /* * Always stop accesses beyond the struct that contains the * field, when the buffer's remaining size is known. - * (The -1 test is to optimize away checks where the buffer + * (The SIZE_MAX test is to optimize away checks where the buffer * lengths are unknown.) */ - if ((p_size != (size_t)(-1) && p_size < size) || - (q_size != (size_t)(-1) && q_size < size)) + 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); \ - fortify_memcpy_chk(__fortify_size, p_size, q_size, \ - p_size_field, q_size_field, #op); \ + const size_t __fortify_size = (size_t)(size); \ + const size_t __p_size = (p_size); \ + const size_t __q_size = (q_size); \ + const size_t __p_size_field = (p_size_field); \ + const size_t __q_size_field = (q_size_field); \ + 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); \ }) /* - * __builtin_object_size() must be captured here to avoid evaluating argument - * side-effects further into the macro layers. + * 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, \ - __builtin_object_size(p, 0), __builtin_object_size(q, 0), \ - __builtin_object_size(p, 1), __builtin_object_size(q, 1), \ + __struct_size(p), __struct_size(q), \ + __member_size(p), __member_size(q), \ memcpy) #define memmove(p, q, s) __fortify_memcpy_chk(p, q, s, \ - __builtin_object_size(p, 0), __builtin_object_size(q, 0), \ - __builtin_object_size(p, 1), __builtin_object_size(q, 1), \ + __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) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __struct_size(p); - if (__builtin_constant_p(size) && p_size < size) + if (__compiletime_lessthan(p_size, size)) __read_overflow(); if (p_size < size) fortify_panic(__func__); @@ -406,13 +644,13 @@ __FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t 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) { - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); + size_t p_size = __struct_size(p); + size_t q_size = __struct_size(q); if (__builtin_constant_p(size)) { - if (p_size < size) + if (__compiletime_lessthan(p_size, size)) __read_overflow(); - if (q_size < size) + if (__compiletime_lessthan(q_size, size)) __read_overflow2(); } if (p_size < size || q_size < size) @@ -423,9 +661,9 @@ int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t __FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3) void *memchr(const void * const POS0 p, int c, __kernel_size_t size) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __struct_size(p); - if (__builtin_constant_p(size) && p_size < size) + if (__compiletime_lessthan(p_size, size)) __read_overflow(); if (p_size < size) fortify_panic(__func__); @@ -435,41 +673,58 @@ void *memchr(const void * const POS0 p, int c, __kernel_size_t 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) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __struct_size(p); - if (__builtin_constant_p(size) && p_size < size) + 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); +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) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __struct_size(p); - if (__builtin_constant_p(size) && p_size < size) + 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) { - size_t p_size = __builtin_object_size(p, 1); - size_t q_size = __builtin_object_size(q, 1); + size_t p_size = __member_size(p); + size_t q_size = __member_size(q); size_t size; /* If neither buffer size is known, immediately give up. */ - if (p_size == (size_t)-1 && q_size == (size_t)-1) + 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 (__builtin_constant_p(size) && p_size < size) + if (__compiletime_lessthan(p_size, size)) __write_overflow(); /* Run-time check for dynamic size overflow. */ if (p_size < size) |