[PATCH 3.16 062/134] [media] ttusb2: limit messages to buffer size

Ben Hutchings
2017-08-18T13:15:46Z

From: Alyssa Milburn <amilburn@zall.org>

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: Ben Hutchings <ben@decadent.org.uk>
---
drivers/media/usb/dvb-usb/ttusb2.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

--- 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_dev
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_ad
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;