cx231xx-cards: fix NULL-deref at probe

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@conexant.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 40 insertions, 5 deletions

diff --git a/drivers/media/usb/cx231xx/cx231xx-cards.c b/drivers/media/usb/cx231xx/cx231xx-cards.c
index 36bc25494319..be9e3335dcb7 100644
--- a/drivers/media/usb/cx231xx/cx231xx-cards.c
+++ b/drivers/media/usb/cx231xx/cx231xx-cards.c
@@ -1397,6 +1397,9 @@ static int cx231xx_init_v4l2(struct cx231xx *dev,
 
         uif = udev->actconfig->interface[idx];
 
+        if (uif->altsetting[0].desc.bNumEndpoints < isoc_pipe + 1)
+                return -ENODEV;
+
         dev->video_mode.end_point_addr = uif->altsetting[0].endpoint[isoc_pipe].desc.bEndpointAddress;
         dev->video_mode.num_alt = uif->num_altsetting;
 
@@ -1410,7 +1413,12 @@ static int cx231xx_init_v4l2(struct cx231xx *dev,
                 return -ENOMEM;
 
         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);
                 dev_dbg(dev->dev,
                         "Alternate setting %i, max size= %i\n", i,
@@ -1427,6 +1435,9 @@ static int cx231xx_init_v4l2(struct cx231xx *dev,
         }
         uif = udev->actconfig->interface[idx];
 
+        if (uif->altsetting[0].desc.bNumEndpoints < isoc_pipe + 1)
+                return -ENODEV;
+
         dev->vbi_mode.end_point_addr =
             uif->altsetting[0].endpoint[isoc_pipe].desc.
                         bEndpointAddress;
@@ -1443,8 +1454,12 @@ static int cx231xx_init_v4l2(struct cx231xx *dev,
                 return -ENOMEM;
 
         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);
@@ -1464,6 +1479,9 @@ static int cx231xx_init_v4l2(struct cx231xx *dev,
         }
         uif = udev->actconfig->interface[idx];
 
+        if (uif->altsetting[0].desc.bNumEndpoints < isoc_pipe + 1)
+                return -ENODEV;
+
         dev->sliced_cc_mode.end_point_addr =
             uif->altsetting[0].endpoint[isoc_pipe].desc.
                         bEndpointAddress;
@@ -1478,7 +1496,12 @@ static int cx231xx_init_v4l2(struct cx231xx *dev,
                 return -ENOMEM;
 
         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);
@@ -1647,6 +1670,11 @@ static int cx231xx_usb_probe(struct usb_interface *interface,
                 }
                 uif = udev->actconfig->interface[idx];
 
+                if (uif->altsetting[0].desc.bNumEndpoints < isoc_pipe + 1) {
+                        retval = -ENODEV;
+                        goto err_video_alt;
+                }
+
                 dev->ts1_mode.end_point_addr =
                     uif->altsetting[0].endpoint[isoc_pipe].
                                 desc.bEndpointAddress;
@@ -1664,7 +1692,14 @@ static int cx231xx_usb_probe(struct usb_interface *interface,
                 }
 
                 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] =