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A heap overflow, heap overrun, or heap smashing is a type of buffer overflow that occurs in the heap data area. Heap overflows are exploitable in a different manner to that of stack-based overflows. Memory on the heap is dynamically allocated at runtime and typically contains program data.
Heap pollution in Java can occur when type arguments and variables are not reified at run-time. As a result, different parameterized types are implemented by the same class or interface at run time. All invocations of a given generic type declaration share a single run-time implementation. This results in the possibility of heap pollution. [2]
Automatic memory management in the form of garbage collection is the most common technique for preventing some of the memory safety problems, since it prevents common memory safety errors like use-after-free for all data allocated within the language runtime. [11]
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 heap bounds, it is referring to memory that is not then possessed by the program. Using such pointers is a ...
A heap spray by itself cannot be used to break any security boundaries: a separate security issue is needed. Exploiting security issues is often hard because various factors can influence this process. Chance alignments of memory and timing introduce a lot of randomness (from the attacker's point of view).
Tombstones are a mechanism to detect dangling pointers and mitigate the problems they can cause in computer programs. Dangling pointers can appear in certain computer programming languages, e.g. C, C++ and assembly languages. A tombstone is a structure that acts as an intermediary between a pointer and its target, often heap-dynamic data in memory.
The techniques to exploit a buffer overflow vulnerability vary by architecture, operating system, and memory region. For example, exploitation on the heap (used for dynamically allocated memory), differs markedly from exploitation on the call stack. In general, heap exploitation depends on the heap manager used on the target system, while stack ...
The garbage-first collector (G1) is a garbage collection algorithm introduced in the Oracle HotSpot Java virtual machine (JVM) 6 and supported from 7 Update 4. It was planned to replace concurrent mark sweep collector (CMS) in JVM 7 and was made default in Java 9.