dw2102: limit messages to buffer size

commit 950e252cb469f323740d78e4907843acef89eedb upstream.

Otherwise the i2c transfer functions can read or write beyond the end of
stack or 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, 54 insertions, 0 deletions

diff --git a/drivers/media/usb/dvb-usb/dw2102.c b/drivers/media/usb/dvb-usb/dw2102.c
index c3e67347a977..4a0cc54870c7 100644
--- a/drivers/media/usb/dvb-usb/dw2102.c
+++ b/drivers/media/usb/dvb-usb/dw2102.c
@@ -205,6 +205,20 @@ static int dw2102_serit_i2c_transfer(struct i2c_adapter *adap,
 
         switch (num) {
         case 2:
+                if (msg[0].len != 1) {
+                        warn("i2c rd: len=%d is not 1!\n",
+                             msg[0].len);
+                        num = -EOPNOTSUPP;
+                        break;
+                }
+
+                if (2 + msg[1].len > sizeof(buf6)) {
+                        warn("i2c rd: len=%d is too big!\n",
+                             msg[1].len);
+                        num = -EOPNOTSUPP;
+                        break;
+                }
+
                 /* read si2109 register by number */
                 buf6[0] = msg[0].addr << 1;
                 buf6[1] = msg[0].len;
@@ -220,6 +234,13 @@ static int dw2102_serit_i2c_transfer(struct i2c_adapter *adap,
         case 1:
                 switch (msg[0].addr) {
                 case 0x68:
+                        if (2 + msg[0].len > sizeof(buf6)) {
+                                warn("i2c wr: len=%d is too big!\n",
+                                     msg[0].len);
+                                num = -EOPNOTSUPP;
+                                break;
+                        }
+
                         /* write to si2109 register */
                         buf6[0] = msg[0].addr << 1;
                         buf6[1] = msg[0].len;
@@ -263,6 +284,13 @@ static int dw2102_earda_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg ms
                 /* first write first register number */
                 u8 ibuf[MAX_XFER_SIZE], obuf[3];
 
+                if (2 + msg[0].len != sizeof(obuf)) {
+                        warn("i2c rd: len=%d is not 1!\n",
+                             msg[0].len);
+                        ret = -EOPNOTSUPP;
+                        goto unlock;
+                }
+
                 if (2 + msg[1].len > sizeof(ibuf)) {
                         warn("i2c rd: len=%d is too big!\n",
                              msg[1].len);
@@ -463,6 +491,12 @@ static int dw3101_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[],
                 /* first write first register number */
                 u8 ibuf[MAX_XFER_SIZE], obuf[3];
 
+                if (2 + msg[0].len != sizeof(obuf)) {
+                        warn("i2c rd: len=%d is not 1!\n",
+                             msg[0].len);
+                        ret = -EOPNOTSUPP;
+                        goto unlock;
+                }
                 if (2 + msg[1].len > sizeof(ibuf)) {
                         warn("i2c rd: len=%d is too big!\n",
                              msg[1].len);
@@ -697,6 +731,13 @@ static int su3000_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[],
                         msg[0].buf[0] = state->data[1];
                         break;
                 default:
+                        if (3 + msg[0].len > sizeof(state->data)) {
+                                warn("i2c wr: len=%d is too big!\n",
+                                     msg[0].len);
+                                num = -EOPNOTSUPP;
+                                break;
+                        }
+
                         /* always i2c write*/
                         state->data[0] = 0x08;
                         state->data[1] = msg[0].addr;
@@ -712,6 +753,19 @@ static int su3000_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg msg[],
                 break;
         case 2:
                 /* always i2c read */
+                if (4 + msg[0].len > sizeof(state->data)) {
+                        warn("i2c rd: len=%d is too big!\n",
+                             msg[0].len);
+                        num = -EOPNOTSUPP;
+                        break;
+                }
+                if (1 + msg[1].len > sizeof(state->data)) {
+                        warn("i2c rd: len=%d is too big!\n",
+                             msg[1].len);
+                        num = -EOPNOTSUPP;
+                        break;
+                }
+
                 state->data[0] = 0x09;
                 state->data[1] = msg[0].len;
                 state->data[2] = msg[1].len;