DivestOS/Patches/Linux_CVEs/CVE-2017-0507/ANY/0.patch

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index cc1b3bf..48b6b86 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -16,6 +16,8 @@
  *
  */
 
+#include <linux/atomic.h>
+#include <linux/err.h>
 #include <linux/file.h>
 #include <linux/freezer.h>
 #include <linux/fs.h>
@@ -400,6 +402,15 @@
 	kref_get(&handle->ref);
 }
 
+/* Must hold the client lock */
+static struct ion_handle* ion_handle_get_check_overflow(struct ion_handle *handle)
+{
+	if (atomic_read(&handle->ref.refcount) + 1 == 0)
+		return ERR_PTR(-EOVERFLOW);
+	ion_handle_get(handle);
+	return handle;
+}
+
 int ion_handle_put_nolock(struct ion_handle *handle)
 {
 	int ret;
@@ -445,9 +456,9 @@
 
 	handle = idr_find(&client->idr, id);
 	if (handle)
-		ion_handle_get(handle);
+		return ion_handle_get_check_overflow(handle);
 
-	return handle ? handle : ERR_PTR(-EINVAL);
+	return ERR_PTR(-EINVAL);
 }
 
 struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
@@ -1339,7 +1350,7 @@
 	/* if a handle exists for this buffer just take a reference to it */
 	handle = ion_handle_lookup(client, buffer);
 	if (!IS_ERR(handle)) {
-		ion_handle_get(handle);
+		handle = ion_handle_get_check_overflow(handle);
 		mutex_unlock(&client->lock);
 		goto end;
 	}