Contents
- 1 What is memory safe code?
- 2 What is considered to be a violation of memory safety?
- 3 How do you ensure memory safety in safe programming languages?
- 4 Why is type safety important?
- 5 What does type unsafe mean?
- 6 Why is C so unsafe?
- 7 How are memory safety checks performed in C?
- 8 Which is the best description of memory safety?
What is memory safe code?
Memory safety is a property of programming languages where all memory access is well defined. Most programming languages in use today are memory-safe because they use some form of garbage collection.
What is considered to be a violation of memory safety?
As with our first definition, we have a notion of defined (allocated) and undefined (never-allocated or deallocated) memory, where we assume deallocated memory is never reused, and memory safety is violated if undefined memory is accessed.
How do you ensure memory safety in safe programming languages?
In general, memory safety can be safely assured using tracing garbage collection and the insertion of runtime checks on every memory access; this approach has overhead, but less than that of Valgrind. All garbage-collected languages take this approach.
What is type safety in programming?
In computer science, type safety is the extent to which a programming language discourages or prevents type errors. The behaviors classified as type errors by a given programming language are usually those that result from attempts to perform operations on values that are not of the appropriate data type.
Why is C not safe?
C and C++ are unsafe in a strong sense: executing an erroneous operation causes the entire program to be meaningless, as opposed to just the erroneous operation having an unpredictable result. In these languages erroneous operations are said to have undefined behavior.
Why is type safety important?
Type safety is really important since it means we have defined behaviour for operations. This allows us to have a safe language, not just for making sure that types are (in some respect) correct but stops various vectors of attack (like accessing outside the bounds of an array).
What does type unsafe mean?
An example of a type-unsafe programming language is C: reading / writing an array value outside of the array’s bounds has an undefined behaviour by specification. It’s impossible to predict what will happen. C is a language that has a type system, but is not type safe.
Why is C so unsafe?
C does not have any of these protections: C heap values are created in a type-unsafe way. C casts, unchecked array accesses, and unsafe deallocation can corrupt memory during its lifetime. C deallocation is unsafe, and can lead to dangling pointers.
Why is memory safety a property of programming languages?
Memory safety is a property of programming languages where all memory access is well defined. Most programming languages in use today are memory-safe because they use some form of garbage collection.
Is it possible to write memory safe code?
While many experienced programmers can write correct systems-level code, it’s clear that no matter the amount of mitigations put in place, it is near impossible to write memory-safe code using traditional systems-level programming languages at scale.
How are memory safety checks performed in C?
All garbage-collected languages take this approach. For C and C++, many tools exist that perform a compile-time transformation of the code to do memory safety checks at runtime, such as CheckPointer and AddressSanitizer which imposes an average slowdown factor of 2.
Which is the best description of memory safety?
For hardware protection of memory, see Memory protection. Memory 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.