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_exit_task(current) call that is performed in install_exec_creds() during privileged execve() calls. This issue affects kernel versions before 4.8.

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_exit_task(current) call that is performed in install_exec_creds() during privileged execve() calls. This issue affects kernel versions before 4.8.

Una condición de carrera en la función perf_event_open() permite a los atacantes locales filtrar datos confidenciales desde los programas setuid. Como no se mantienen bloqueos relevantes (en particular, la función cred_guard_mutex) durante la llamada ptrace_may_access(), es posible que la tarea de destino especificada realice un syscall execve() con la ejecución setuid anterior a que perf_event_alloc() realmente se conecte, permitiendo que un atacante omita la comprobación ptrace_may_access() y la llamada perf_event_exit_task(current) que se realiza en install_exec_creds() durante las llamadas privilegiadas execve(). Este problema afecta a las versiones del kernel versión anterior a 4.8.