CVE-2023-23586

A use-after-free vulnerability was discovered in the Linux kernel’s io_uring subsystem. It was found that it is possible to insert a time namespace’s vvar page to process memory space via a page fault. When this time namespace is destroyed, the vvar page is also freed, but not removed from the process’ memory, and a next page allocated by the kernel will be still available from the user-space process. This (read-only) use-after-free vulnerability can lead to kernel memory leak.