[Dropped cc to stable and LKML.]
On Tue, 2017-05-23 at 22:09 +0200, Greg Kroah-Hartman wrote:
> 4.4-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Alyssa Milburn <amilburn@xxxxxxxx>
>
> commit a12b8ab8c5ff7ccd7b107a564743507c850a441d upstream.
>
> Otherwise ttusb2_i2c_xfer can read or write beyond the end of static and
> heap buffers.
This function has another problem: it uses per-device mutexes to guard
access to static buffers. This only works as long as there's a single
device. It should be using per-device buffers (or a static mutex, but
that's less good).
Ben.
> Signed-off-by: Alyssa Milburn <amilburn@xxxxxxxx>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>
> ---
> 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;
>
>
>
--
Ben Hutchings
Software Developer, Codethink Ltd.
