Linux-libre 4.7.5-gnupck-4.7.5-gnu

1 files changed, 17 insertions, 0 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 297d6854f..e68286121 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2334,6 +2334,23 @@ out:
 	return ret;
 }
 
+/*
+ * Drop the (possibly final) reference to task->mempolicy.  It needs to be
+ * dropped after task->mempolicy is set to NULL so that any allocation done as
+ * part of its kmem_cache_free(), such as by KASAN, doesn't reference a freed
+ * policy.
+ */
+void mpol_put_task_policy(struct task_struct *task)
+{
+	struct mempolicy *pol;
+
+	task_lock(task);
+	pol = task->mempolicy;
+	task->mempolicy = NULL;
+	task_unlock(task);
+	mpol_put(pol);
+}
+
 static void sp_delete(struct shared_policy *sp, struct sp_node *n)
 {
 	pr_debug("deleting %lx-l%lx\n", n->start, n->end);