An attacker can block any read() access to /proc/PID/cmdline by mmap()ing a FUSE file (Filesystem in Userspace) onto this process's command-line arguments. The attacker can therefore block pgrep, pidof, pkill, ps, and w, either forever (a denial of service), or for some controlled time (a synchronization tool for exploiting other vulnerabilities). https://security.archlinux.org/CVE-2018-1120 https://www.securityfocus.com/bid/104229/discuss https://www.qualys.com/2018/05/17/procps-ng-audit-report-advisory.txt
