CVE-2026-68448 ovl: check access to copy_file_range source with src mounter creds

In the Linux kernel, the following vulnerability has been resolved: ovl: check access to copyfilerange source with src mounter creds Commit 5dae222a5ff0c "vfs: allow copyfilerange to copy across devices" allowed filesystems that implement the copyfilerange fop to decide if they want to access...