[PATCH 3.13 072/103] USB: serial: fix potential heap buffer overflow

[Kamal Mostafa]

3.13.11.8 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan at kernel.org>

commit 5654699fb38512bdbfc0f892ce54fce75bdc2bab upstream.

Make sure to verify the number of ports requested by subdriver to avoid
writing beyond the end of fixed-size array in interface data.

The current usb-serial implementation is limited to eight ports per
interface but failed to verify that the number of ports requested by a
subdriver (which could have been determined from device descriptors) did
not exceed this limit.

Signed-off-by: Johan Hovold <johan at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/usb/serial/usb-serial.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index c08151d..cb6eff2 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -862,6 +862,11 @@ static int usb_serial_probe(struct usb_interface *interface,
 			num_ports = type->num_ports;
 	}
 
+	if (num_ports > MAX_NUM_PORTS) {
+		dev_warn(ddev, "too many ports requested: %d\n", num_ports);
+		num_ports = MAX_NUM_PORTS;
+	}
+
 	serial->num_ports = num_ports;
 	serial->num_bulk_in = num_bulk_in;
 	serial->num_bulk_out = num_bulk_out;
-- 
1.9.1