From 237564961047194a9d952292197ccc794264cab7 Mon Sep 17 00:00:00 2001
From: Haogang Chen <haogangchen@gmail.com>
Date: Tue, 29 Nov 2011 18:32:25 -0300
Subject: [PATCH 074/130] uvcvideo: Fix integer overflow in
 uvc_ioctl_ctrl_map()

commit 806e23e95f94a27ee445022d724060b9b45cb64a upstream.

There is a potential integer overflow in uvc_ioctl_ctrl_map(). When a
large xmap->menu_count is passed from the userspace, the subsequent call
to kmalloc() will allocate a buffer smaller than expected.
map->menu_count and map->menu_info would later be used in a loop (e.g.
in uvc_query_v4l2_ctrl), which leads to out-of-bound access.

The patch checks the ioctl argument and returns -EINVAL for zero or too
large values in xmap->menu_count.

Signed-off-by: Haogang Chen <haogangchen@gmail.com>
[laurent.pinchart@ideasonboard.com Prevent excessive memory consumption]
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 drivers/media/video/uvc/uvc_v4l2.c |    9 +++++++++
 drivers/media/video/uvc/uvcvideo.h |    1 +
 2 files changed, 10 insertions(+)

diff --git a/drivers/media/video/uvc/uvc_v4l2.c b/drivers/media/video/uvc/uvc_v4l2.c
index dadf11f..cf7788f 100644
--- a/drivers/media/video/uvc/uvc_v4l2.c
+++ b/drivers/media/video/uvc/uvc_v4l2.c
@@ -58,6 +58,15 @@ static int uvc_ioctl_ctrl_map(struct uvc_video_chain *chain,
 		break;
 
 	case V4L2_CTRL_TYPE_MENU:
+		/* Prevent excessive memory consumption, as well as integer
+		 * overflows.
+		 */
+		if (xmap->menu_count == 0 ||
+		    xmap->menu_count > UVC_MAX_CONTROL_MENU_ENTRIES) {
+			ret = -EINVAL;
+			goto done;
+		}
+
 		size = xmap->menu_count * sizeof(*map->menu_info);
 		map->menu_info = kmalloc(size, GFP_KERNEL);
 		if (map->menu_info == NULL) {
diff --git a/drivers/media/video/uvc/uvcvideo.h b/drivers/media/video/uvc/uvcvideo.h
index 4c1392e..bc446ba 100644
--- a/drivers/media/video/uvc/uvcvideo.h
+++ b/drivers/media/video/uvc/uvcvideo.h
@@ -113,6 +113,7 @@
 
 /* Maximum allowed number of control mappings per device */
 #define UVC_MAX_CONTROL_MAPPINGS	1024
+#define UVC_MAX_CONTROL_MENU_ENTRIES	32
 
 /* Devices quirks */
 #define UVC_QUIRK_STATUS_INTERVAL	0x00000001
-- 
1.7.9.4

