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A stack buffer overflow can be caused deliberately as part of an attack known as stack smashing. If the affected program is running with special privileges, or accepts data from untrusted network hosts (e.g. a webserver ) then the bug is a potential security vulnerability .
Additionally, a peek operation can, without modifying the stack, return the value of the last element added. The name stack is an analogy to a set of physical items stacked one atop another, such as a stack of plates. The order in which an element added to or removed from a stack is described as last in, first out, referred to by the acronym LIFO.
In Java, thread-local variables are implemented by the ThreadLocal class object. [15] ThreadLocal holds variable of type T, [15] which is accessible via get/set methods. For example, ThreadLocal variable holding Integer value looks like this:
The stack is often used to store variables of fixed length local to the currently active functions. Programmers may further choose to explicitly use the stack to store local data of variable length. If a region of memory lies on the thread's stack, that memory is said to have been allocated on the stack, i.e. stack-based memory allocation (SBMA).
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.
discard the top two values on the stack (or one value, if it is a double or long) putfield b5 1011 0101 2: indexbyte1, indexbyte2 objectref, value → set field to value in an object objectref, where the field is identified by a field reference index in constant pool (indexbyte1 << 8 | indexbyte2) putstatic b3 1011 0011 2: indexbyte1, indexbyte2
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 .
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.