[PATCH 4.4 01/52] staging: ion: Prevent incorrect reference counting behavour

[Greg Kroah-Hartman]

From: Lee Jones <lee.jones@xxxxxxxxxx>

Supply additional checks in order to prevent unexpected results.

Fixes: b892bf75b2034 ("ion: Switch ion to use dma-buf")
Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/staging/android/ion/ion.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -606,6 +606,9 @@ static void *ion_buffer_kmap_get(struct
 	void *vaddr;
 
 	if (buffer->kmap_cnt) {
+		if (buffer->kmap_cnt == INT_MAX)
+			return ERR_PTR(-EOVERFLOW);
+
 		buffer->kmap_cnt++;
 		return buffer->vaddr;
 	}
@@ -626,6 +629,9 @@ static void *ion_handle_kmap_get(struct
 	void *vaddr;
 
 	if (handle->kmap_cnt) {
+		if (handle->kmap_cnt == INT_MAX)
+			return ERR_PTR(-EOVERFLOW);
+
 		handle->kmap_cnt++;
 		return buffer->vaddr;
 	}