cx231xx-audio: fix NULL-deref at probe

commit 65f921647f4c89a2068478c89691f39b309b58f7 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, 15 insertions, 2 deletions

diff --git a/drivers/media/usb/cx231xx/cx231xx-audio.c b/drivers/media/usb/cx231xx/cx231xx-audio.c
index 2ca713b1c086..bf4b3ca2abf9 100644
--- a/drivers/media/usb/cx231xx/cx231xx-audio.c
+++ b/drivers/media/usb/cx231xx/cx231xx-audio.c
@@ -701,6 +701,11 @@ static int cx231xx_audio_init(struct cx231xx *dev)
                                             hs_config_info[0].interface_info.
                                             audio_index + 1];
 
+        if (uif->altsetting[0].desc.bNumEndpoints < isoc_pipe + 1) {
+                err = -ENODEV;
+                goto err_free_card;
+        }
+
         adev->end_point_addr =
             uif->altsetting[0].endpoint[isoc_pipe].desc.
                         bEndpointAddress;
@@ -716,8 +721,14 @@ static int cx231xx_audio_init(struct cx231xx *dev)
         }
 
         for (i = 0; i < adev->num_alt; i++) {
-                u16 tmp =
-                    le16_to_cpu(uif->altsetting[i].endpoint[isoc_pipe].desc.
+                u16 tmp;
+
+                if (uif->altsetting[i].desc.bNumEndpoints < isoc_pipe + 1) {
+                        err = -ENODEV;
+                        goto err_free_pkt_size;
+                }
+
+                tmp = le16_to_cpu(uif->altsetting[i].endpoint[isoc_pipe].desc.
                                 wMaxPacketSize);
                 adev->alt_max_pkt_size[i] =
                     (tmp & 0x07ff) * (((tmp & 0x1800) >> 11) + 1);
@@ -728,6 +739,8 @@ static int cx231xx_audio_init(struct cx231xx *dev)
 
         return 0;
 
+err_free_pkt_size:
+        kfree(adev->alt_max_pkt_size);
 err_free_card:
         snd_card_free(card);