Messages in this thread | | | Subject | Re: [PATCH 1/5] comedi: ni_usb6501: fix NULL-deref in command paths | From | Ian Abbott <> | Date | Tue, 26 Oct 2021 15:12:28 +0100 |
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On 25/10/2021 12:45, 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 | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/comedi/drivers/ni_usb6501.c b/drivers/comedi/drivers/ni_usb6501.c > index 5b6d9d783b2f..eb2e5c23f25d 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, > @@ -486,12 +490,16 @@ static int ni6501_find_endpoints(struct comedi_device *dev) > ep_desc = &iface_desc->endpoint[i].desc; > > if (usb_endpoint_is_bulk_in(ep_desc)) { > + if (usb_endpoint_maxp(ep_desc) < RX_MAX_SIZE) > + continue; > if (!devpriv->ep_rx) > devpriv->ep_rx = ep_desc; > continue; > } > > if (usb_endpoint_is_bulk_out(ep_desc)) { > + if (usb_endpoint_maxp(ep_desc) < TX_MAX_SIZE) > + continue; > if (!devpriv->ep_tx) > devpriv->ep_tx = ep_desc; > continue; >
Perhaps it should return an error if the first encountered bulk-in endpoint has the wrong size or the first encountered bulk-out endpoint has the wrong size. Something like:
if (usb_endpoint_is_bulk_in(ep_desc)) { if (!devpriv->ep_rx) { if (usb_endpoint_maxp(ep_desc) < RX_MAX_SIZE) break; } continue;
(similar for bulk-out with TX_MAX_SIZE)
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