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Stack buffer overflow. In software, a stack buffer overflow or stack buffer overrun 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. [1][2] Stack buffer overflow bugs are caused when a program writes more data to a buffer located on the ...
Definitions. A string is defined as a contiguous sequence of code units terminated by the first zero code unit (often called the NUL code unit). [1] This means a string cannot contain the zero code unit, as the first one seen marks the end of the string. The length of a string is the number of code units before the zero code unit. [1]
Here is an example of ANSI C code that will generally cause a segmentation fault on platforms with memory protection. It attempts to modify a string literal, which is undefined behavior according to the ANSI C standard. Most compilers will not catch this at compile time, and instead compile this to executable code that will crash:
In the example, 1 & 2 were the first to enter the circular buffer, they are the first to be removed, leaving 3 inside of the buffer. If the buffer has 7 elements, then it is completely full: A property of the circular buffer is that when it is full and a subsequent write is performed, then it starts overwriting the oldest data.
In programming and information security, a buffer overflow or buffer overrun is an anomaly whereby a program writes data to a buffer beyond the buffer's allocated memory, overwriting adjacent memory locations. Buffers are areas of memory set aside to hold data, often while moving it from one section of a program to another, or between programs.
In the C programming language, an escape sequence is specially delimited text in a character or string literal that represents one or more other characters to the compiler. It allows a programmer to specify characters that are otherwise difficult or impossible to specify in a literal. An escape sequence starts with a backslash (\) called the ...
Canaries or canary words or stack cookies are known values that are placed between a buffer and control data on the stack to monitor buffer overflows. When the buffer overflows, the first data to be corrupted will usually be the canary, and a failed verification of the canary data will therefore alert of an overflow, which can then be handled, for example, by invalidating the corrupted data.
Resource acquisition is initialization (RAII) [1] is a programming idiom [2] used in several object-oriented, statically typed programming languages to describe a particular language behavior. In RAII, holding a resource is a class invariant, and is tied to object lifetime. Resource allocation (or acquisition) is done during object creation ...