prctl: make PR_SET_TIMERSLACK_PID pid namespace aware

Make PR_SET_TIMERSLACK_PID consider pid namespace and resolve the
target pid in the caller's namespace. Otherwise, calls from pid
namespace other than init would fail or affect the wrong task.

Change-Id: I1da15196abc4096536713ce03714e99d2e63820a
Signed-off-by: Micha Kalfon <micha@cellrox.com>
Acked-by: Oren Laadan <orenl@cellrox.com>

diff --git a/kernel/sys.c b/kernel/sys.c
index 0f45fb855fe36821a01f543b95e56a08f838e6b9..66b933a5c061f2880af255e45b1af455d8818170 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2220,11 +2220,11 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
                error = prctl_get_tid_address(me, (int __user **)arg2);
                break;
        case PR_SET_TIMERSLACK_PID:
-               if (current->pid != (pid_t)arg3 &&
+               if (task_pid_vnr(current) != (pid_t)arg3 &&
                                !capable(CAP_SYS_NICE))
                        return -EPERM;
                rcu_read_lock();
-               tsk = find_task_by_pid_ns((pid_t)arg3, &init_pid_ns);
+               tsk = find_task_by_vpid((pid_t)arg3);
                if (tsk == NULL) {
                        rcu_read_unlock();
                        return -EINVAL;