I have been working on a new functionality for the prctl syscall that addresses a common security concern with container runtimes. The /proc/self/exe symlink, which points to the executable of the running process, was the key ingredient in CVE-2019-5736, a vulnerability that allowed a malicious container to overwrite the container runtime binary on the host. The workaround deployed at the time — re-execing from a copy or using a read-only bind mount — treats the symptom rather than the cause.