[PATCH 1/1] staging: ion: Prevent incorrect reference counting behavour

[Lee Jones <lee.jones@xxxxxxxxxx>]

Supply additional checks in order to prevent unexpected results.

Fixes: b892bf75b2034 ("ion: Switch ion to use dma-buf")
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
---
 drivers/staging/android/ion/ion.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 806e9b30b9dc8..30f359faba575 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -509,6 +509,9 @@ static void *ion_handle_kmap_get(struct ion_handle *handle)
 	void *vaddr;
 
 	if (handle->kmap_cnt) {
+		if (handle->kmap_cnt + 1 < handle->kmap_cnt)
+			return ERR_PTR(-EOVERFLOW);
+
 		handle->kmap_cnt++;
 		return buffer->vaddr;
 	}
-- 
2.34.0.rc2.393.gf8c9666880-goog