Final answer:
Stack Smashing Protection (SSP) or stack protection is a GCC compiler extension aimed at preventing buffer overflow attacks by checking a canary value placed on the stack to ensure the return address of a function has not been altered.
Step-by-step explanation:
The protection mechanism being referred to is Stack Smashing Protection (SSP) or stack protection. This is a GCC (GNU Compiler Collection) compiler extension that aims to prevent a common vulnerability in C and C++ programs known as buffer overflow. By inserting additional code at the beginning and end of functions, it checks that the return address of a function has not been altered, which is an indicator of a buffer overflow attack.
This security feature works by placing a special value, called a canary, on the stack right before the return address when a function is called. Upon function exit, the compiler checks if the canary's value has been changed. If it has, the program can assume a stack smashing attack has occurred and take appropriate action, such as terminating the program.