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Memory Leak
#REDIRECT Memory_leak
Abstract
Memory is allocated but never freed.
Description
Memory leaks have two common and sometimes overlapping causes:
- Error conditions and other exceptional circumstances.
- Confusion over which part of the program is responsible for freeing the memory
Most memory leaks result in general software reliability problems, but if an attacker can intentionally trigger a memory leak, the attacker might be able to launch a denial of service attack (by crashing the program) or take advantage of other unexpected program behavior resulting from a low memory condition [1].
Examples
The following C function leaks a block of allocated memory if the call to read() fails to return the expected number of bytes:
char* getBlock(int fd) {
char* buf = (char*) malloc(BLOCK_SIZE);
if (!buf) {
return NULL;
}
if (read(fd, buf, BLOCK_SIZE) != BLOCK_SIZE) {
return NULL;
}
return buf;
}
Related Threats
Related Attacks
Category:Denial of Service Attack
Related Vulnerabilities
Related Countermeasures
References
[1] J. Whittaker and H. Thompson. How to Break Software Security. Addison Wesley, 2003.
