Memory corruption occurs in a

computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer progra ...

when the contents of a

memory location In computing, a memory address is a reference to a specific memory location used at various levels by software and hardware. Memory addresses are fixed-length sequences of digits conventionally displayed and manipulated as unsigned integers. Su ...

are modified due to programmatic behavior that exceeds the intention of the original

programmer A computer programmer, sometimes referred to as a software developer, a software engineer, a programmer or a coder, is a person who creates computer programs — often for larger computer software. A programmer is someone who writes/creates ...

or program/language constructs; this is termed as violation of

memory safety safety is the state of being protected from various software bugs and security vulnerabilities when dealing with memory access, such as buffer overflows and dangling pointers. For example, Java is said to be memory-safe because its runtime error ...

. The most likely causes of memory corruption are programming errors (software bugs). When the corrupted memory contents are used later in that program, it leads either to program crash or to strange and bizarre program behavior. Nearly 10% of application crashes on Windows systems are due to

heap Heap or HEAP may refer to: Computing and mathematics * Heap (data structure), a data structure commonly used to implement a priority queue * Heap (mathematics), a generalization of a group * Heap (programming) (or free store), an area of memory f ...

corruption.{{Cite web, last=Radich, first=Q., last2=Sherer, first2=T., last3=Sharkey, first3=K., last4=Batchelor, first4=D., last5=Kennedy, first5=J. T., last6=Mabee, first6=D., last7=Coulter, first7=D., last8=Michael, first8=S., date=28 April 2021, title=Application Verifier (Windows 7 and Windows Server 2008 R2 Application Quality Cookbook) - Win32 apps, publisher=Microsoft Developer Network, url=https://docs.microsoft.com/en-us/windows/win32/win7appqual/application-verifier, access-date=2022-02-09, language=en-us Modern programming languages like C and C++ have powerful features of explicit memory management and pointer arithmetic. These features are designed for developing efficient applications and system software. However, using these features incorrectly may lead to memory corruption errors. Memory corruption is one of the most intractable class of programming errors, for two reasons: #The source of the memory corruption and its manifestation may be far apart, making it hard to correlate the cause and the effect. #Symptoms appear under unusual conditions, making it hard to consistently reproduce the error. Memory corruption errors can be broadly classified into four categories: #Using uninitialized memory: Contents of uninitialized memory are treated as garbage values. Using such values can lead to unpredictable program behavior. #Using non-owned memory: It is common to use pointers to access and modify memory. If such a pointer is a null pointer, dangling pointer (pointing to memory that has already been freed), or to a memory location outside of current stack or

bounds, it is referring to memory that is not then possessed by the program. Using such pointers is a serious programming flaw. Accessing such memory usually causes operating system exceptions, that most commonly lead to a program crash (unless suitable memory protection software is being used). #Using memory beyond the memory that was allocated (

buffer overflow In information security and programming, a buffer overflow, or buffer overrun, is an anomaly whereby a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations. Buffers are areas of memor ...

): If an array is used in a loop, with incorrect terminating condition, memory beyond the array bounds may be accidentally manipulated. Buffer overflow is one of the most common programming flaws exploited by computer viruses, causing serious

computer security Computer security, cybersecurity (cyber security), or information technology security (IT security) is the protection of computer systems and networks from attack by malicious actors that may result in unauthorized information disclosure, t ...

issues (e.g. return-to-libc attack,

stack-smashing protection Buffer overflow protection is any of various techniques used during software development to enhance the security of executable programs by detecting buffer overflows on stack-allocated variables, and preventing them from causing program misbehavior ...

) in widely used programs. In some cases programs can also incorrectly access the memory before the start of a buffer. #Faulty heap memory management:

Memory leak In computer science, a memory leak is a type of resource leak that occurs when a computer program incorrectly manages memory allocations in a way that memory which is no longer needed is not released. A memory leak may also happen when an object ...

s and freeing non-heap or un-allocated memory are the most frequent errors caused by faulty heap memory management. Many memory debuggers such as Purify,

Valgrind Valgrind () is a programming tool for memory debugging, memory leak detection, and profiling. Valgrind was originally designed to be a free memory debugging tool for Linux on x86, but has since evolved to become a generic framework for creati ...

, Insure++, Parasoft C/C++test, AddressSanitizer are available to detect memory corruption errors.

References

External links

Memory Corruption Tutorial
An introduction to exploitation techniques and protection mechanisms Software bugs Computer memory Computer security exploitsbr>

See also

References

External links