In case you wondered why Linus recently fiddled with the user mode stack expansion code in mainline[1], here is your explanation:

CVE-2023-3269. #LinuxKernel privilege escalation vulnerability – openwall.com/lists/oss-securit

"#StackRot is a #Linux #kernel vulnerability found in the memory management subsystem [of 6.1 - 6.4], it affects almost all configurations and requires minimal capabilities to trigger"

[1] git.kernel.org/torvalds/c/9471 , which was followed by several fix-up patches in the past week