3 ms·

If you're at byte 4095 and you advance by 1 byte and the next page is a guard page, you're dead. You can minimize the risk of this by requiring that input addr

If you're at byte 4095 and you advance by 1 byte and the next page is a guard page, you're dead. You can minimize the risk of this by requiring that input addresses be aligned (and many ABIs/APIs do require this) but it's realistic to say that an extra byte of lookahead can and will SIGSEGV in unfortunate cases.

mehrdadn 6y ago
What I'm saying is that the compiler can generate code that examines the memory address and looks ahead only when it's safe to do so.
- saurik 6y ago
  (And for those who think this is strange, memcpy implementations usually do this, so there is precedent that this is very sane.)
  - BeeOnRope 6y ago
    memcpy doesn't have this same problem because it is known-length without any early exit.