Integer Overflow

Description

Check the size of your integers, considering what would happen if it wrapped around
Watch the casting - don’t just ignore those compiler warnings!
Libraries such as SafeInt or BigInteger might be more suitable if the problem is very complex.
Having a well-placed integrity check built into your design can reduce the messiness of checking every single operation.

A wraparound combined with a malloc operation can result in a zero-sized buffer being allocated - leading to a zero-byte buffer, which will always be overflowed.
In practice, most integer wraparounds come from improper casting, not as much from math operations.
Always checking every integer for wraparound after every arithmetic operation is impractical. Pay attention to which integers wrapping around would have security implications.
Wraparound doesn’t have security effects on every integer, but on more than you may think.

  $ cd integer-overflow
  $ make