[PATCH v1 1/1] USB: serial: Add boundry check for read_urbs array access

[sathyanarayanan . kuppuswamy]

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>

In usb_serial_generic_submit_read_urb() function we are accessing the
port->read_urbs array without any boundry checks. This might lead to
kernel panic when index value goes above array length.

One posible call path for this issue is,

usb_serial_generic_read_bulk_callback()
{
 ...
 if (!port->throttled) {
	usb_serial_generic_submit_read_urb(port, i, GFP_ATOMIC);
 ...
}

This patch fixes this issue.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---
 drivers/usb/serial/generic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 2274d96..72ebdde 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -306,6 +306,9 @@ static int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
 {
 	int res;
 
+	if (index >= ARRAY_SIZE(port->read_urbs))
+		return -EINVAL;
+
 	if (!test_and_clear_bit(index, &port->read_urbs_free))
 		return 0;
 
-- 
2.7.4