From: Lee Jones <lee.jones@linaro.org>
Date: Fri, 26 Nov 2021 10:33:35 +0000 (+0000)
Subject: staging: ion: Prevent incorrect reference counting behavour
X-Git-Tag: v4.4.294~52
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0801decc8053851b06e8fb32c39c19c247c1cad2;p=thirdparty%2Fkernel%2Fstable.git

staging: ion: Prevent incorrect reference counting behavour

Supply additional checks in order to prevent unexpected results.

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>
---

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 4adb1138af09b..f2b875ccf388f 100644
--- 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 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;
 	}
@@ -626,6 +629,9 @@ static void *ion_handle_kmap_get(struct ion_handle *handle)
 	void *vaddr;
 
 	if (handle->kmap_cnt) {
+		if (handle->kmap_cnt == INT_MAX)
+			return ERR_PTR(-EOVERFLOW);
+
 		handle->kmap_cnt++;
 		return buffer->vaddr;
 	}