A stack overflow protection method and device

Abstract

The invention provides a stack overflow protection method, by inserting a buffer into the stack, and filling the buffer with filling characters in the format of "fixed character string + random character string" or "random character string+fixed character string" String, and check the filling value in the buffer when the stack is released, which solves the problem of poor defense against stack overflow vulnerabilities, thereby reducing the risk of attackers using stack overflow vulnerabilities to damage the system. The invention also includes a stack overflow protection device.

Description

technical field [0001] The invention relates to the field of computers, in particular to a stack overflow protection method and device. Background technique [0002] The construction and development of computer technology and the Internet have brought huge impetus and impact to the economy, culture, technology and other aspects of the entire society. A large number of information systems such as telecommunications, e-commerce, and financial networks have become the key foundation of the country and the government. facilities, so how to ensure the security of computer systems has become an urgent problem in front of us. [0003] The stack overflow vulnerability is an extremely serious system security vulnerability. It destroys the system memory space by writing too long data into a limited memory space, causing the system to run abnormally, crash or restart. Through the stack overflow attack, the address of the attack code is used to overwrite the function pointer, allowing ...

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Problems solved by technology

Although this method can detect overflow, it uses fixed characters to fill the position of Canaries that can be easily detected by attackers, and skips the buffer and directly modifies the subsequent data. In this case, the overflow protection is invalid.

[0012] The second method is to generate a random number and store it in a memory page that is not mapped into the virtual address space. A segment fault will occur when trying to access the memory that stores the random number through a pointer, but this random number It will eventually be saved in the function stack as Canaries, so the attacker still has a chance to obtain the value of the random number

However, this method involves a lot of calculations, and the calculation of Canaries consumes too much

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