releases/4.9.30/ttusb2-limit-messages-to-buffer-size.patch

   1 From a12b8ab8c5ff7ccd7b107a564743507c850a441d Mon Sep 17 00:00:00 2001
   2 From: Alyssa Milburn <amilburn@zall.org>
   3 Date: Sat, 1 Apr 2017 14:34:32 -0300
   4 Subject: [media] ttusb2: limit messages to buffer size
   5
   6 From: Alyssa Milburn <amilburn@zall.org>
   7
   8 commit a12b8ab8c5ff7ccd7b107a564743507c850a441d upstream.
   9
  10 Otherwise ttusb2_i2c_xfer can read or write beyond the end of static and
  11 heap buffers.
  12
  13 Signed-off-by: Alyssa Milburn <amilburn@zall.org>
  14 Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
  15 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  16
  17 ---
  18  drivers/media/usb/dvb-usb/ttusb2.c |   19 +++++++++++++++++++
  19  1 file changed, 19 insertions(+)
  20
  21 --- a/drivers/media/usb/dvb-usb/ttusb2.c
  22 +++ b/drivers/media/usb/dvb-usb/ttusb2.c
  23 @@ -78,6 +78,9 @@ static int ttusb2_msg(struct dvb_usb_dev
  24         u8 *s, *r = NULL;
  25         int ret = 0;
  26
  27 +       if (4 + rlen > 64)
  28 +               return -EIO;
  29 +
  30         s = kzalloc(wlen+4, GFP_KERNEL);
  31         if (!s)
  32                 return -ENOMEM;
  33 @@ -381,6 +384,22 @@ static int ttusb2_i2c_xfer(struct i2c_ad
  34                 write_read = i+1 < num && (msg[i+1].flags & I2C_M_RD);
  35                 read = msg[i].flags & I2C_M_RD;
  36
  37 +               if (3 + msg[i].len > sizeof(obuf)) {
  38 +                       err("i2c wr len=%d too high", msg[i].len);
  39 +                       break;
  40 +               }
  41 +               if (write_read) {
  42 +                       if (3 + msg[i+1].len > sizeof(ibuf)) {
  43 +                               err("i2c rd len=%d too high", msg[i+1].len);
  44 +                               break;
  45 +                       }
  46 +               } else if (read) {
  47 +                       if (3 + msg[i].len > sizeof(ibuf)) {
  48 +                               err("i2c rd len=%d too high", msg[i].len);
  49 +                               break;
  50 +                       }
  51 +               }
  52 +
  53                 obuf[0] = (msg[i].addr << 1) | (write_read | read);
  54                 if (read)
  55                         obuf[1] = 0;