diff --git a/fs/proc/base.c b/fs/proc/base.c
index 32c7f7d69267893d8a3fcd7811040241df8575d6..e43c1c9480cba9923adf3661792628c9a364f56c 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2564,6 +2564,10 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
 	void *page;
 	int rv;
 
+	/* A task may only write when it was the opener. */
+	if (file->f_cred != current_real_cred())
+		return -EPERM;
+
 	rcu_read_lock();
 	task = pid_task(proc_pid(inode), PIDTYPE_PID);
 	if (!task) {