diff options
Diffstat (limited to 'lib/libc')
| -rw-r--r-- | lib/libc/string/strcpy.3 | 54 |
1 files changed, 0 insertions, 54 deletions
diff --git a/lib/libc/string/strcpy.3 b/lib/libc/string/strcpy.3 index ba764d7..f74f8b8 100644 --- a/lib/libc/string/strcpy.3 +++ b/lib/libc/string/strcpy.3 @@ -157,60 +157,6 @@ to arbitrarily change a running program's functionality through a buffer overflow attack. (See the FSA.) -.Pp -Avoid using -.Fn strcpy . -Instead, use -.Fn strncpy -or -.Fn strlcpy -and ensure that no more characters are copied to the destination buffer -than it can hold. -Don't forget to NUL-terminate the destination buffer, -as -.Fn strncpy -will not terminate the destination string if it is truncated. -.Pp -Note that -.Fn strncpy -can also be problematic. -It may be a security concern for a string to be -truncated at all. -Since the truncated string will not be as long as the original, -it may refer to a completely different resource -and usage of the truncated resource -could result in very incorrect behavior. -Example: -.Pp -.Bd -literal -void -foo(const char *arbitrary_string) -{ - char onstack[8]; - -#if defined(BAD) - /* - * This first strcpy is bad behavior. Don't use strcpy()! - */ - (void)strcpy(onstack, arbitrary_string); /* BAD! */ -#elif defined(BETTER) - /* - * The following two lines demonstrate better use of - * strncpy(). - */ - (void)strncpy(onstack, arbitrary_string, sizeof(onstack) - 1); - onstack[sizeof(onstack - 1)] = '\\0'; -#elif defined(BEST) - /* - * These lines are even more robust due to testing for - * truncation. - */ - if (strlen(arbitrary_string) + 1 > sizeof(onstack)) - err(1, "onstack would be truncated"); - (void)strncpy(onstack, arbitrary_string, sizeof(onstack)); -#endif -} -.Ed .Sh SEE ALSO .Xr bcopy 3 , .Xr memccpy 3 , |
