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@xxxxxxxxxxxxxxx # 3.18
Cc: Luca Ellero <luca.ellero@xxxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
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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