USB: serial: fix potential stack buffer overflow

Make sure to verify the maximum number of endpoints per type to avoid
writing beyond the end of a stack-allocated array.

The current usb-serial implementation is limited to eight ports per
interface but failed to verify that the number of endpoints of a certain
type reported by a device did not exceed this limit.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 02de3110fe940e63308e7707a966c539bb620403..eb0e8c6a86828c9ae9523956bf42a5c87670fc2a 100644 (file)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -764,29 +764,39 @@ static int usb_serial_probe(struct usb_interface *interface,
                if (usb_endpoint_is_bulk_in(endpoint)) {
                        /* we found a bulk in endpoint */
                        dev_dbg(ddev, "found bulk in on endpoint %d\n", i);
-                       bulk_in_endpoint[num_bulk_in] = endpoint;
-                       ++num_bulk_in;
+                       if (num_bulk_in < MAX_NUM_PORTS) {
+                               bulk_in_endpoint[num_bulk_in] = endpoint;
+                               ++num_bulk_in;
+                       }
                }
 
                if (usb_endpoint_is_bulk_out(endpoint)) {
                        /* we found a bulk out endpoint */
                        dev_dbg(ddev, "found bulk out on endpoint %d\n", i);
-                       bulk_out_endpoint[num_bulk_out] = endpoint;
-                       ++num_bulk_out;
+                       if (num_bulk_out < MAX_NUM_PORTS) {
+                               bulk_out_endpoint[num_bulk_out] = endpoint;
+                               ++num_bulk_out;
+                       }
                }
 
                if (usb_endpoint_is_int_in(endpoint)) {
                        /* we found a interrupt in endpoint */
                        dev_dbg(ddev, "found interrupt in on endpoint %d\n", i);
-                       interrupt_in_endpoint[num_interrupt_in] = endpoint;
-                       ++num_interrupt_in;
+                       if (num_interrupt_in < MAX_NUM_PORTS) {
+                               interrupt_in_endpoint[num_interrupt_in] =
+                                               endpoint;
+                               ++num_interrupt_in;
+                       }
                }
 
                if (usb_endpoint_is_int_out(endpoint)) {
                        /* we found an interrupt out endpoint */
                        dev_dbg(ddev, "found interrupt out on endpoint %d\n", i);
-                       interrupt_out_endpoint[num_interrupt_out] = endpoint;
-                       ++num_interrupt_out;
+                       if (num_interrupt_out < MAX_NUM_PORTS) {
+                               interrupt_out_endpoint[num_interrupt_out] =
+                                               endpoint;
+                               ++num_interrupt_out;
+                       }
                }
        }
 
@@ -809,8 +819,10 @@ static int usb_serial_probe(struct usb_interface *interface,
                                if (usb_endpoint_is_int_in(endpoint)) {
                                        /* we found a interrupt in endpoint */
                                        dev_dbg(ddev, "found interrupt in for Prolific device on separate interface\n");
-                                       interrupt_in_endpoint[num_interrupt_in] = endpoint;
-                                       ++num_interrupt_in;
+                                       if (num_interrupt_in < MAX_NUM_PORTS) {
+                                               interrupt_in_endpoint[num_interrupt_in] = endpoint;
+                                               ++num_interrupt_in;
+                                       }
                                }
                        }
                }