linux-kernel - [PATCH 3.2 20/59] [media] cx231xx-cards: fix NULL-deref at probe

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Date:   Fri, 18 Aug 2017 14:13:13 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Mauro Carvalho Chehab" <mchehab@...pensource.com>,
        "Hans Verkuil" <hans.verkuil@...co.com>,
        "Sri Deevi" <Srinivasa.Deevi@...exant.com>,
        "Johan Hovold" <johan@...nel.org>
Subject: [PATCH 3.2 20/59] [media] cx231xx-cards: fix NULL-deref at probe

3.2.92-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@...nel.org>

commit 0cd273bb5e4d1828efaaa8dfd11b7928131ed149 upstream.

Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer or accessing memory beyond the endpoint array should a
malicious device lack the expected endpoints.

Fixes: e0d3bafd0258 ("V4L/DVB (10954): Add cx231xx USB driver")

Cc: Sri Deevi <Srinivasa.Deevi@...exant.com>
Signed-off-by: Johan Hovold <johan@...nel.org>
Signed-off-by: Hans Verkuil <hans.verkuil@...co.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/media/video/cx231xx/cx231xx-cards.c | 45 +++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 5 deletions(-)

--- a/drivers/media/video/cx231xx/cx231xx-cards.c
+++ b/drivers/media/video/cx231xx/cx231xx-cards.c
@@ -1159,6 +1159,9 @@ static int cx231xx_usb_probe(struct usb_
 	uif = udev->actconfig->interface[dev->current_pcb_config.
 		       hs_config_info[0].interface_info.video_index + 1];
 
+	if (uif->altsetting[0].desc.bNumEndpoints < isoc_pipe + 1)
+		return -ENODEV;
+
 	dev->video_mode.end_point_addr = le16_to_cpu(uif->altsetting[0].
 			endpoint[isoc_pipe].desc.bEndpointAddress);
 
@@ -1176,8 +1179,12 @@ static int cx231xx_usb_probe(struct usb_
 	}
 
 	for (i = 0; i < dev->video_mode.num_alt; i++) {
-		u16 tmp = le16_to_cpu(uif->altsetting[i].endpoint[isoc_pipe].
-				desc.wMaxPacketSize);
+		u16 tmp;
+
+		if (uif->altsetting[i].desc.bNumEndpoints < isoc_pipe + 1)
+			return -ENODEV;
+
+		tmp = le16_to_cpu(uif->altsetting[i].endpoint[isoc_pipe].desc.wMaxPacketSize);
 		dev->video_mode.alt_max_pkt_size[i] =
 		    (tmp & 0x07ff) * (((tmp & 0x1800) >> 11) + 1);
 		cx231xx_info("Alternate setting %i, max size= %i\n", i,
@@ -1189,6 +1196,9 @@ static int cx231xx_usb_probe(struct usb_
 				       hs_config_info[0].interface_info.
 				       vanc_index + 1];
 
+	if (uif->altsetting[0].desc.bNumEndpoints < isoc_pipe + 1)
+		return -ENODEV;
+
 	dev->vbi_mode.end_point_addr =
 	    le16_to_cpu(uif->altsetting[0].endpoint[isoc_pipe].desc.
 			bEndpointAddress);
@@ -1207,8 +1217,12 @@ static int cx231xx_usb_probe(struct usb_
 	}
 
 	for (i = 0; i < dev->vbi_mode.num_alt; i++) {
-		u16 tmp =
-		    le16_to_cpu(uif->altsetting[i].endpoint[isoc_pipe].
+		u16 tmp;
+
+		if (uif->altsetting[i].desc.bNumEndpoints < isoc_pipe + 1)
+			return -ENODEV;
+
+		tmp = le16_to_cpu(uif->altsetting[i].endpoint[isoc_pipe].
 				desc.wMaxPacketSize);
 		dev->vbi_mode.alt_max_pkt_size[i] =
 		    (tmp & 0x07ff) * (((tmp & 0x1800) >> 11) + 1);
@@ -1221,6 +1235,9 @@ static int cx231xx_usb_probe(struct usb_
 				       hs_config_info[0].interface_info.
 				       hanc_index + 1];
 
+	if (uif->altsetting[0].desc.bNumEndpoints < isoc_pipe + 1)
+		return -ENODEV;
+
 	dev->sliced_cc_mode.end_point_addr =
 	    le16_to_cpu(uif->altsetting[0].endpoint[isoc_pipe].desc.
 			bEndpointAddress);
@@ -1239,7 +1256,12 @@ static int cx231xx_usb_probe(struct usb_
 	}
 
 	for (i = 0; i < dev->sliced_cc_mode.num_alt; i++) {
-		u16 tmp = le16_to_cpu(uif->altsetting[i].endpoint[isoc_pipe].
+		u16 tmp;
+
+		if (uif->altsetting[i].desc.bNumEndpoints < isoc_pipe + 1)
+			return -ENODEV;
+
+		tmp = le16_to_cpu(uif->altsetting[i].endpoint[isoc_pipe].
 				desc.wMaxPacketSize);
 		dev->sliced_cc_mode.alt_max_pkt_size[i] =
 		    (tmp & 0x07ff) * (((tmp & 0x1800) >> 11) + 1);
@@ -1254,6 +1276,11 @@ static int cx231xx_usb_probe(struct usb_
 					       interface_info.
 					       ts1_index + 1];
 
+		if (uif->altsetting[0].desc.bNumEndpoints < isoc_pipe + 1) {
+			retval = -ENODEV;
+			goto err_video_alt;
+		}
+
 		dev->ts1_mode.end_point_addr =
 		    le16_to_cpu(uif->altsetting[0].endpoint[isoc_pipe].
 				desc.bEndpointAddress);
@@ -1272,7 +1299,14 @@ static int cx231xx_usb_probe(struct usb_
 		}
 
 		for (i = 0; i < dev->ts1_mode.num_alt; i++) {
-			u16 tmp = le16_to_cpu(uif->altsetting[i].
+			u16 tmp;
+
+			if (uif->altsetting[i].desc.bNumEndpoints < isoc_pipe + 1) {
+				retval = -ENODEV;
+				goto err_video_alt;
+			}
+
+			tmp = le16_to_cpu(uif->altsetting[i].
 						endpoint[isoc_pipe].desc.
 						wMaxPacketSize);
 			dev->ts1_mode.alt_max_pkt_size[i] =