Pätkävirhe

Pätkävirhe is a term used in Finnish computing to describe a segmentation fault, a runtime error that occurs when a program attempts to access memory outside its allocated address space or perform an illegal memory operation. When a pätkävirhe occurs, the operating system typically terminates the program and may generate a core dump or an error signal such as SIGSEGV.

Causes of pätkävirhe include dereferencing null or uninitialized pointers, accessing arrays outside their bounds, using memory after it has been freed, buffer overflows, or writing to read-only memory. Stack corruption and fraudulent pointer arithmetic can also trigger the fault. Such errors are often hard to reproduce because they depend on specific memory layouts and execution timing.

Symptoms and debugging approaches: a sudden program termination, a trace or crash report mentioning a segmentation fault, or an unexpected debugger stop at a particular instruction. Debugging tools commonly used to locate the fault include debuggers (for example gdb), memory checkers (such as Valgrind), and sanitizers (AddressSanitizer). Typical strategies for diagnosis involve compiling with debugging symbols, checking pointer initialization, validating array indices, and reviewing manual memory management.

Prevention and safety: memory-safe languages or runtime checks reduce the risk of pätkävirheit. In languages like C and C++, careful pointer handling, bounds checking, and safer abstractions help; compiler and platform features such as address space separation, NX protections, and ASLR also contribute to mitigation.

See also: segmentation fault; memory safety; null pointer dereference; SIGSEGV.