CVE 2019-3901
A race condition in perf_event_open() allows local attackers to leak sensitive data from setuid programs. As no relevant locks (in particular the cred_guard_mutex) are held during the ptrace_may_access() call, it is possible for the specified target task to perform an execve() syscall with setuid execution before perf_event_alloc() actually attaches to it, allowing an attacker to bypass the ptrace_may_access() check and the perf_event_
See the
CVE page on Mitre.org
for more details.