Editing Buffer overflow (section)

===Use of safe libraries===

The problem of buffer overflows is common in the C and C++ languages because they expose low level representational details of buffers as containers for data types. Buffer overflows can be avoided by maintaining a high degree of correctness in code that performs buffer management. It has also long been recommended to avoid standard library functions that are not bounds checked, such as <code>[[gets()|gets]]</code>, <code>[[scanf]]</code> and <code>[[strcpy]]</code>. The [[Morris worm]] exploited a <code>gets</code> call in [[fingerd]].<ref>{{cite web |url=http://wiretap.area.com/Gopher/Library/Techdoc/Virus/inetvir.823 |title=Archived copy |website=wiretap.area.com |access-date=6 June 2022 |archive-url=https://web.archive.org/web/20010505080457/http://wiretap.area.com/Gopher/Library/Techdoc/Virus/inetvir.823 |archive-date=5 May 2001 |url-status=dead}}</ref>

Well-written and tested abstract data type libraries that centralize and automatically perform buffer management, including bounds checking, can reduce the occurrence and impact of buffer overflows. The primary data types in languages in which buffer overflows are common are strings and arrays. Thus, libraries preventing buffer overflows in these data types can provide the vast majority of the necessary coverage. However, failure to use these safe libraries correctly can result in buffer overflows and other vulnerabilities, and naturally any [[Software bug|bug]] in the library is also a potential vulnerability. "Safe" library implementations include "The Better String Library",<ref>{{cite web |url=http://bstring.sf.net/ |title=The Better String Library}}</ref> Vstr<ref>{{cite web |url=http://www.and.org/vstr/ |title=The Vstr Homepage |access-date=2007-05-15 |archive-url=https://web.archive.org/web/20170305020810/http://www.and.org/vstr/ |archive-date=2017-03-05 |url-status=dead }}</ref> and Erwin.<ref>{{cite web |url=http://www.theiling.de/projects/erwin.html |title=The Erwin Homepage |access-date=2007-05-15}}</ref> The [[OpenBSD]] operating system's [[C library]] provides the [[strlcpy]] and [[strlcat]] functions, but these are more limited than full safe library implementations.

In September 2007, Technical Report 24731, prepared by the C standards committee, was published.<ref>{{Cite web|url=https://www.iso.org/obp/ui/#iso:std:iso-iec:tr:24731:-1:ed-2:v1:en:sec:4|title=Information technology – Programming languages, their environments and system software interfaces – Extensions to the C library – Part 1: Bounds-checking interfaces|last=International Organization for Standardization|date=2007|website=ISO Online Browsing Platform}}</ref> It specifies a set of functions that are based on the standard C library's string and IO functions, with additional buffer-size parameters. However, the efficacy of these functions for reducing buffer overflows is disputable. They require programmer intervention on a per function call basis that is equivalent to intervention that could make the analogous older standard library functions buffer overflow safe.<ref>{{cite web |url=https://www.securecoding.cert.org/confluence/x/QwY |archive-url=https://archive.today/20121228031633/https://www.securecoding.cert.org/confluence/x/QwY |url-status=dead |archive-date=December 28, 2012 |title=CERT Secure Coding Initiative |access-date=2007-07-30 }}</ref>