This is a challenge compiled with an old version of Rust compiler.
The first hint is meant to let everybody have a grasp of why the source code can't compile on newer versions of Rust compiler and leads them to the right direction.
After figuring out why the source can't compile, players can :
- Wandering around the broken part of the code and try to trigger the bug.
- Search for references of the fix (or issue) related to this problem.
- Do whatever they like to "learn" about the bug. :)
After players know there is a use-after-free bug, the common exploitation thoughts are to retake some important structures that can achieve memory read/write. So they need to study for some Rust internals.
Details can be found in : x.py