[PATCH 3.16 035/134] [media] cx231xx-cards: fix NULL-deref at probe

Ben Hutchings
2017-08-18T13:15:44Z

From: Johan Hovold <johan@kernel.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@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>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/media/usb/cx231xx/cx231xx-cards.c | 45 +++++++++++++++++++++++++++----
1 file changed, 40 insertions(+), 5 deletions(-)

--- a/drivers/media/usb/cx231xx/cx231xx-cards.c
+++ b/drivers/media/usb/cx231xx/cx231xx-cards.c
@@ -1258,6 +1258,9 @@ 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 = uif->altsetting[0].
endpoint[isoc_pipe].desc.bEndpointAddress;

@@ -1275,8 +1278,12 @@ 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,
@@ -1288,6 +1295,9 @@ 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 =
uif->altsetting[0].endpoint[isoc_pipe].desc.
bEndpointAddress;
@@ -1306,8 +1316,12 @@ 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);
@@ -1320,6 +1334,9 @@ 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 =
uif->altsetting[0].endpoint[isoc_pipe].desc.
bEndpointAddress;
@@ -1338,7 +1355,12 @@ 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);
@@ -1353,6 +1375,11 @@ 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 =
uif->altsetting[0].endpoint[isoc_pipe].
desc.bEndpointAddress;
@@ -1371,7 +1398,14 @@ 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] =