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[1] [2] 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, and in cases where the overflow was triggered by mistake, will often cause the program to crash or operate ...
Similarly to a stack of plates, adding or removing is only practical at the top. Simple representation of a stack runtime with push and pop operations.. In computer science, a stack is an abstract data type that serves as a collection of elements with two main operations:
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.
When a function executes, it may add some of its local state data to the top of the stack; when the function exits it is responsible for removing that data from the stack. At a minimum, a thread's stack is used to store the location of a return address provided by the caller in order to allow return statements to return to the correct location.
Stronger stack protection is possible by splitting the stack in two: one for data and one for function returns. This split is present in the Forth language, though it was not a security-based design decision. Regardless, this is not a complete solution to buffer overflows, as sensitive data other than the return address may still be overwritten.
At function return, the stack pointer is instead restored to the frame pointer, the value of the stack pointer just before the function was called. Each stack frame contains a stack pointer to the top of the frame immediately below. The stack pointer is a mutable register shared between all invocations. A frame pointer of a given invocation of ...
C++ changes some C standard library functions to add additional overloaded functions with const type qualifiers, e.g. strchr returns char* in C, while C++ acts as if there were two overloaded functions const char *strchr(const char *) and a char *strchr(char *). In C23 generic selection is used to make C's behaviour more similar to C++'s. [11]
In computing, a stack trace (also called stack backtrace [1] or stack traceback [2]) is a report of the active stack frames at a certain point in time during the execution of a program. When a program is run, memory is often dynamically allocated in two places: the stack and the heap. Memory is continuously allocated on a stack but not on a ...