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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.
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.
Visualization of a software buffer overflow. Data is written into A, but is too large to fit within A, so it overflows into B.. 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.
Many other programming languages, such as Java, do not automatically prevent memory-based race conditions, yet are still generally considered "memory safe" languages. Therefore, countering race conditions is generally not considered necessary for a language to be considered memory safe.
Allocating more memory on the stack than is available can result in a crash due to stack overflow. This is also why functions that use alloca are usually prevented from being inlined: [ 2 ] should such a function be inlined into a loop, the caller would suffer from an unanticipated growth in stack usage, making an overflow much more likely.
Stack Overflow is a question-and-answer website for computer programmers. It is the flagship site of the Stack Exchange Network . [ 2 ] [ 3 ] [ 4 ] It was created in 2008 by Jeff Atwood and Joel Spolsky .
If a push operation causes the stack pointer to increment or decrement beyond the maximum extent of the stack, a stack overflow occurs. Some environments that rely heavily on stacks may provide additional operations, for example: Duplicate: the top item is popped and then pushed twice, such that two copies of the former top item now lie at the top.
In computer science, a data buffer (or just buffer) is a region of memory used to store data temporarily while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device (such as a microphone) or just before it is sent to an output device (such as speakers); however, a buffer may be used when data is moved between processes ...