CVE-2022-49852

In the Linux kernel, the following vulnerability has been resolved:

riscv: process: fix kernel info leakage

threadstruct's s[12] may contain random kernel memory content, which may be finally leaked to userspace. This is a security hole. Fix it by clearing the s[12] array in threadstruct when fork.

As for kthread case, it's better to clear the s[12] array as well.