ttusb2: limit messages to buffer size

commit a12b8ab8c5ff7ccd7b107a564743507c850a441d upstream.

Otherwise ttusb2_i2c_xfer can read or write beyond the end of static and
heap buffers.

Signed-off-by: Alyssa Milburn <amilburn@zall.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/media/usb/dvb-usb/ttusb2.c b/drivers/media/usb/dvb-usb/ttusb2.c
index ecc207fbaf3c..9e0d6a4166d2 100644
--- a/drivers/media/usb/dvb-usb/ttusb2.c
+++ b/drivers/media/usb/dvb-usb/ttusb2.c
@@ -78,6 +78,9 @@ static int ttusb2_msg(struct dvb_usb_device *d, u8 cmd,
         u8 *s, *r = NULL;
         int ret = 0;
 
+        if (4 + rlen > 64)
+                return -EIO;
+
         s = kzalloc(wlen+4, GFP_KERNEL);
         if (!s)
                 return -ENOMEM;
@@ -381,6 +384,22 @@ static int ttusb2_i2c_xfer(struct i2c_adapter *adap,struct i2c_msg msg[],int num
                 write_read = i+1 < num && (msg[i+1].flags & I2C_M_RD);
                 read = msg[i].flags & I2C_M_RD;
 
+                if (3 + msg[i].len > sizeof(obuf)) {
+                        err("i2c wr len=%d too high", msg[i].len);
+                        break;
+                }
+                if (write_read) {
+                        if (3 + msg[i+1].len > sizeof(ibuf)) {
+                                err("i2c rd len=%d too high", msg[i+1].len);
+                                break;
+                        }
+                } else if (read) {
+                        if (3 + msg[i].len > sizeof(ibuf)) {
+                                err("i2c rd len=%d too high", msg[i].len);
+                                break;
+                        }
+                }
+
                 obuf[0] = (msg[i].addr << 1) | (write_read | read);
                 if (read)
                         obuf[1] = 0;