USB: serial: fix potential stack buffer overflow

commit d979e9f9ecab04c1ecca741370e30a8a498893f5 upstream.

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.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 8f76a2b..8a47ffd 100644 (file)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -791,29 +791,39 @@ int usb_serial_probe(struct usb_interface *interface,
                if (usb_endpoint_is_bulk_in(endpoint)) {
                        /* we found a bulk in endpoint */
                        dbg("found bulk in on endpoint %d", 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 */
                        dbg("found bulk out on endpoint %d", 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 */
                        dbg("found interrupt in on endpoint %d", 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 */
                        dbg("found interrupt out on endpoint %d", 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;
+                       }
                }
        }
 
@@ -836,8 +846,10 @@ int usb_serial_probe(struct usb_interface *interface,
                                if (usb_endpoint_is_int_in(endpoint)) {
                                        /* we found a interrupt in endpoint */
                                        dbg("found interrupt in for Prolific device on separate interface");
-                                       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;
+                                       }
                                }
                        }
                }