On 27/10/2021 10:35, Johan Hovold wrote:

The driver uses endpoint-sized USB transfer buffers but had no sanity checks on the sizes. This can lead to zero-size-pointer dereferences or overflowed transfer buffers in ni6501_port_command() and ni6501_counter_command() if a (malicious) device has smaller max-packet sizes than expected (or when doing descriptor fuzz testing).

Add the missing sanity checks to probe().

Fixes: a03bb00e50ab ("staging: comedi: add NI USB-6501 support") Cc: stable@vger.kernel.org # 3.18 Cc: Luca Ellero luca.ellero@brickedbrain.com Signed-off-by: Johan Hovold johan@kernel.org

---

drivers/comedi/drivers/ni_usb6501.c | 10 ++++++++++ 1 file changed, 10 insertions(+)

diff --git a/drivers/comedi/drivers/ni_usb6501.c b/drivers/comedi/drivers/ni_usb6501.c index 5b6d9d783b2f..c42987b74b1d 100644 --- a/drivers/comedi/drivers/ni_usb6501.c +++ b/drivers/comedi/drivers/ni_usb6501.c @@ -144,6 +144,10 @@ static const u8 READ_COUNTER_RESPONSE[] = {0x00, 0x01, 0x00, 0x10, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00}; +/* Largest supported packets */ +static const size_t TX_MAX_SIZE = sizeof(SET_PORT_DIR_REQUEST); +static const size_t RX_MAX_SIZE = sizeof(READ_PORT_RESPONSE);

• enum commands { READ_PORT, WRITE_PORT,

@@ -501,6 +505,12 @@ static int ni6501_find_endpoints(struct comedi_device *dev) if (!devpriv->ep_rx || !devpriv->ep_tx) return -ENODEV;

• if (usb_endpoint_maxp(devpriv->ep_rx) < RX_MAX_SIZE)

• return -ENODEV;
  

• if (usb_endpoint_maxp(devpriv->ep_tx) < TX_MAX_SIZE)

• return -ENODEV;
  

• return 0; }

Looks good, thanks!

Reviewed-by: Ian Abbott abbotti@mev.co.uk