1 files changed, 11 insertions, 2 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index a60459947f18..7f49be94eba9 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1833,8 +1833,6 @@ 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);
@@ -2001,6 +1999,17 @@ static __latent_entropy struct task_struct *copy_process(
                 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!
          */