1 files changed, 21 insertions, 5 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index dcb39bc88f6c..3798b954e6e8 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -351,7 +351,9 @@ static inline struct task_group *task_group(struct task_struct *p)
         struct task_group *tg;
 
 #ifdef CONFIG_USER_SCHED
-        tg = p->user->tg;
+        rcu_read_lock();
+        tg = __task_cred(p)->user->tg;
+        rcu_read_unlock();
 #elif defined(CONFIG_CGROUP_SCHED)
         tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
                                 struct task_group, css);
@@ -5141,6 +5143,22 @@ __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
         set_load_weight(p);
 }
 
+/*
+ * check the target process has a UID that matches the current process's
+ */
+static bool check_same_owner(struct task_struct *p)
+{
+        const struct cred *cred = current_cred(), *pcred;
+        bool match;
+
+        rcu_read_lock();
+        pcred = __task_cred(p);
+        match = (cred->euid == pcred->euid ||
+                 cred->euid == pcred->uid);
+        rcu_read_unlock();
+        return match;
+}
+
 static int __sched_setscheduler(struct task_struct *p, int policy,
                                 struct sched_param *param, bool user)
 {
@@ -5200,8 +5218,7 @@ recheck:
                         return -EPERM;
 
                 /* can't change other user's priorities */
-                if ((current->euid != p->euid) &&
-                    (current->euid != p->uid))
+                if (!check_same_owner(p))
                         return -EPERM;
         }
 
@@ -5433,8 +5450,7 @@ long sched_setaffinity(pid_t pid, const cpumask_t *in_mask)
         read_unlock(&tasklist_lock);
 
         retval = -EPERM;
-        if ((current->euid != p->euid) && (current->euid != p->uid) &&
-                        !capable(CAP_SYS_NICE))
+        if (!check_same_owner(p) && !capable(CAP_SYS_NICE))
                 goto out_unlock;
 
         retval = security_task_setscheduler(p, 0, NULL);