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    Subject[PATCH 3.18 25/59] [media] ttusb2: limit messages to buffer size
    Date
    3.18-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    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;

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