media: dvb-usb: dtv5100: fix out-of-bounds in dtv5100_i2c_msg()

rlen value is a user-controlled value, but dtv5100_i2c_msg() does not
check the size of the rlen value. Therefore, if it is set to a value
larger than sizeof(st->data), an out-of-bounds vuln occurs for st->data.

Therefore, we need to add proper range checking to prevent this vuln.

Fixes: 60688d5e6e6e ("V4L/DVB (8735): dtv5100: replace dummy frontend by zl10353")
Cc: stable@vger.kernel.org
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

diff --git a/drivers/media/usb/dvb-usb/dtv5100.c b/drivers/media/usb/dvb-usb/dtv5100.c
index 3d85c6f7f6ecf401a6e60ed4f5d77f4c510a28fe..c448e2ebda1ac0f84e18572c23710a902de61352 100644 (file)
--- a/drivers/media/usb/dvb-usb/dtv5100.c
+++ b/drivers/media/usb/dvb-usb/dtv5100.c
@@ -55,6 +55,11 @@ static int dtv5100_i2c_msg(struct dvb_usb_device *d, u8 addr,
        }
        index = (addr << 8) + wbuf[0];
 
+       if (rlen > sizeof(st->data)) {
+               warn("rlen = %x is too big!\n", rlen);
+               return -EINVAL;
+       }
+
        memcpy(st->data, rbuf, rlen);
        msleep(1); /* avoid I2C errors */
        return usb_control_msg(d->udev, pipe, request,