Merge branch 'next' into for-linus

1 files changed, 21 insertions, 5 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index e4bb1dd7b308..33cf4a1cbcd1 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -345,7 +345,9 @@ 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);
@@ -5134,6 +5136,22 @@ __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)
 {
@@ -5193,8 +5211,7 @@ 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;
 	}
 
@@ -5426,8 +5443,7 @@ 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);