From 0d752f78b20dbe4eeb9bc76f118889f1898948ca Mon Sep 17 00:00:00 2001
From: Lee Jones <lee.jones@linaro.org>
Date: Mon, 9 May 2022 15:17:10 +0100
Subject: [PATCH] BACKPORT: staging: ion: Prevent incorrect reference counting
 behavour

Supply additional check in order to prevent unexpected results.

Bug: 205573273
Fixes: b892bf75b2034 ("ion: Switch ion to use dma-buf")
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[Lee: Patch now applies to ion_buffer.c instead of ion.c]
Change-Id: Ia6afdd9ca502caa9cad6619d438fc6c8e8457679
(cherry picked from commit fea24b07edfc348c67a019b6e17b39c0698e631f)
---
 drivers/staging/android/ion/ion_buffer.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/android/ion/ion_buffer.c b/drivers/staging/android/ion/ion_buffer.c
index 9baca1a472b6..9c7a353a4220 100644
--- a/drivers/staging/android/ion/ion_buffer.c
+++ b/drivers/staging/android/ion/ion_buffer.c
@@ -249,6 +249,9 @@ void *ion_buffer_kmap_get(struct ion_buffer *buffer)
 	void *vaddr;
 
 	if (buffer->kmap_cnt) {
+		if (buffer->kmap_cnt == INT_MAX)
+			return ERR_PTR(-EOVERFLOW);
+
 		buffer->kmap_cnt++;
 		return buffer->vaddr;
 	}