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{{Short description|Software security techniques}}
'''Buffer overflow protection''' is any of various techniques used during software development to enhance the security of executable programs by detecting [[buffer overflow]]s on [[call stack|stack]]-allocated variables, and preventing them from causing program misbehavior or from becoming serious [[computer security|security]] vulnerabilities. A stack buffer overflow occurs when a program writes to a [[memory address]] on the program's call stack outside of the intended data structure, which is usually a fixed-length buffer. Stack buffer overflow bugs are caused when a program writes more data to a buffer located on the stack than what is actually allocated for that buffer. This almost always results in corruption of adjacent data on the stack, which could lead to program crashes, incorrect operation, or security issues.
Typically, buffer overflow protection modifies the organization of stack-allocated data so it includes a ''[[stack canary|canary]]'' value that, when destroyed by a stack buffer overflow, shows that a buffer preceding it in memory has been overflowed. By verifying the canary value, execution of the affected program can be terminated, preventing it from misbehaving or from allowing an attacker to take control over it. Other buffer overflow protection techniques include ''[[bounds checking]]'', which checks accesses to each allocated block of memory so they cannot go beyond the actually allocated space, and ''tagging'', which ensures that memory allocated for storing data cannot contain executable code.
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All [[Fedora (operating system)|Fedora]] packages are compiled with <kbd>-fstack-protector</kbd> since Fedora Core 5, and <kbd>-fstack-protector-strong</kbd> since Fedora 20.<ref>{{cite web|url=https://fedoraproject.org/wiki/Security_Features#Stack_Smash_Protection.2C_Buffer_Overflow_Detection.2C_and_Variable_Reordering |title=Security Features |publisher=FedoraProject |date=2013-12-11 |access-date=2014-04-27}}</ref><ref>{{cite web|url=https://fedorahosted.org/fesco/ticket/1128 |title=#1128 (switching from "-fstack-protector" to "-fstack-protector-strong" in Fedora 20) – FESCo |publisher=Fedorahosted.org |access-date=2014-04-27}}</ref> Most packages in [[Ubuntu]] are compiled with <kbd>-fstack-protector</kbd> since 6.10.<ref>{{cite web|url=https://wiki.ubuntu.com/Security/Features#stack-protector |title=Security/Features - Ubuntu Wiki |publisher=Wiki.ubuntu.com |access-date=2014-04-27}}</ref> Every [[Arch Linux]] package is compiled with <kbd>-fstack-protector</kbd> since 2011.<ref>{{cite web|url=https://bugs.archlinux.org/task/18864 |title=FS#18864 : Consider enabling GCC's stack-smashing protection (ProPolice, SSP) for all packages |publisher=Bugs.archlinux.org |access-date=2014-04-27}}</ref> All Arch Linux packages built since 4 May 2014 use <kbd>-fstack-protector-strong</kbd>.<ref>{{cite web |url=https://projects.archlinux.org/svntogit/packages.git/commit/trunk?h=packages/pacman&id=695ca25d4c24f3bd3b8c350d64f2697c733d5169 |archive-url=https://archive.today/20140718035407/https://projects.archlinux.org/svntogit/packages.git/commit/trunk?h=packages/pacman&id=695ca25d4c24f3bd3b8c350d64f2697c733d5169 |url-status=dead |archive-date=July 18, 2014 |title=svntogit/packages.git - Git clone of the 'packages' repository }}</ref> Stack protection is only used for some packages in [[Debian]],<ref>{{cite web |url=http://outflux.net/debian/hardening/ |title=Debian Security Hardening Statistics |publisher=Outflux.net |access-date=2014-04-27 |archive-date=2014-04-28 |archive-url=https://web.archive.org/web/20140428012424/http://outflux.net/debian/hardening/ |url-status=dead }}</ref> and only for the [[FreeBSD]] base system since 8.0.<ref>{{cite web|url=http://www.freebsd.org/releases/8.0R/relnotes.html |title=FreeBSD 8.0-RELEASE Release Notes |publisher=Freebsd.org |date=2013-11-13 |access-date=2014-04-27}}</ref> Stack protection is standard in certain operating systems, including [[OpenBSD]],<ref>{{cite web| url = https://man.openbsd.org/gcc-local.1| title = OpenBSD's gcc-local(1) manual page| quote = gcc comes with the ''ProPolice'' stack protection extension, which is enabled by default.}}</ref> [[Hardened Gentoo]]<ref>{{cite web|url=https://wiki.gentoo.org/wiki/Hardened/Toolchain#Default_addition_of_the_Stack_Smashing_Protector_.28SSP.29|title=Hardened/Toolchain - Gentoo Wiki|quote=The Gentoo hardened GCC switches on the stack protector by default unless explicitly requested not to.|date=2016-07-31}}</ref> and [[DragonFly BSD]].{{Citation needed|date=September 2013}}
StackGuard and ProPolice cannot protect against overflows in automatically allocated structures that overflow into function pointers. ProPolice at least will rearrange the allocation order to get such structures allocated before function pointers. A separate mechanism for [[pointer protection]] was proposed in PointGuard<ref>{{cite web|url=http://www.usenix.org/events/sec03/tech/full_papers/cowan/cowan_html/index.html|title=12th USENIX Security Symposium — Technical Paper}}</ref> and is available on [[Microsoft Windows]].<ref>{{cite web|url=http://blogs.msdn.com/michael_howard/archive/2006/08/16/702707.aspx|title=MSDN Blogs – Get the latest information, insights, announcements, and news from Microsoft experts and developers in the MSDN blogs.|date=6 August 2021 }}</ref>
===Microsoft Visual Studio===
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