What is a bus error?


What does the "bus error" message mean, and how does it differ from a segfault?


Answers:


Bus errors are rare nowadays on x86 and occur when your processor cannot even attempt the memory access requested, typically:

  • using a processor instruction with an address that does not satisfy its alignment requirements.

Segmentation faults occur when accessing memory which does not belong to your process, they are very common and are typically the result of:

  • using a pointer to something that was deallocated.
  • using an uninitialized hence bogus pointer.
  • using a null pointer.
  • overflowing a buffer.

PS: To be more precise this is not manipulating the pointer itself that will cause issues, it's accessing the memory it points to (dereferencing).