Understanding memory safety

Aslan Askarov
2026-09-25

A five-panel comic. Two people discuss what memory safe means. One starts writing a list of forbidden behaviors on a whiteboard, says it is easy, and is later found on a stepladder in front of three full whiteboards. The other says that is a list of symptoms. Asked whether there is a definition that is not a list, the first says: for decades, no; since April, yes. It is that a program cannot tell who is handing out the memory, except when they run out and except when there is an explicit cast. That is still a list. It is a list of two, with a proof.

Paper: René Rydhof Hansen, Andreas Stenbæk Larsen, and Aslan Askarov. The Downgrading Semantics of Memory Safety. PLDI 2026.

Drawn in the style of xkcd. Typeface: xkcd Script from the ipython/xkcd-font project, CC BY-NC 3.0.