diff --git a/kernel/fork.c b/kernel/fork.c index f0b58479534f..64ef113e387e 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1784,8 +1784,6 @@ static __latent_entropy struct task_struct *copy_process( posix_cpu_timers_init(p); - p->start_time = ktime_get_ns(); - p->real_start_time = ktime_get_boot_ns(); p->io_context = NULL; audit_set_context(p, NULL); cgroup_fork(p); @@ -1949,6 +1947,17 @@ static __latent_entropy struct task_struct *copy_process( if (retval) goto bad_fork_free_pid; + /* + * From this point on we must avoid any synchronous user-space + * communication until we take the tasklist-lock. In particular, we do + * not want user-space to be able to predict the process start-time by + * stalling fork(2) after we recorded the start_time but before it is + * visible to the system. + */ + + p->start_time = ktime_get_ns(); + p->real_start_time = ktime_get_boot_ns(); + /* * Make it visible to the rest of the system, but dont wake it up yet. * Need tasklist lock for parent etc handling!