CRED: Use RCU to access another task's creds and to release a task's own creds

[linux-2.6-block.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e210526e64010bf599817f7ae69d45ded332ae3e..a512a75a55600896f1dc5782a11c9bdb7f48e948 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1279,7 +1279,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
 static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
 {
        struct task_struct *tsk;
-       uid_t euid;
+       const struct cred *cred = current_cred(), *tcred;
        int ret;
 
        if (pid) {
@@ -1289,16 +1289,16 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
                        rcu_read_unlock();
                        return -ESRCH;
                }
-               get_task_struct(tsk);
-               rcu_read_unlock();
 
-               euid = current_euid();
-               if (euid &&
-                   euid != tsk->cred->uid &&
-                   euid != tsk->cred->suid) {
-                       put_task_struct(tsk);
+               tcred = __task_cred(tsk);
+               if (cred->euid &&
+                   cred->euid != tcred->uid &&
+                   cred->euid != tcred->suid) {
+                       rcu_read_unlock();
                        return -EACCES;
                }
+               get_task_struct(tsk);
+               rcu_read_unlock();
        } else {
                tsk = current;
                get_task_struct(tsk);