linux-kernel - [074/129] [media] uvcvideo: Fix integer overflow in uvc_ioctl_ctrl

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Date:	Mon, 23 Jan 2012 18:34:54 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Haogang Chen <haogangchen@...il.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Mauro Carvalho Chehab <mchehab@...hat.com>
Subject: [074/129] [media] uvcvideo: Fix integer overflow in uvc_ioctl_ctrl_map()

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------
Content-Length: 1836
Lines: 53

From: Haogang Chen <haogangchen@...il.com>

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@...il.com>
[laurent.pinchart@...asonboard.com Prevent excessive memory consumption]
Signed-off-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/media/video/uvc/uvc_v4l2.c |    9 +++++++++
 drivers/media/video/uvc/uvcvideo.h |    1 +
 2 files changed, 10 insertions(+)

--- 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
 		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) {
--- 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


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