[PATCH 5.4 050/222] USB: serial: io_edgeport: add missing active-port sanity check

Greg Kroah-Hartman
2020-01-22T13:18:57Z

From: Johan Hovold <johan@kernel.org>

commit 1568c58d11a7c851bd09341aeefd6a1c308ac40d upstream.

The driver receives the active port number from the device, but never
made sure that the port number was valid. This could lead to a
NULL-pointer dereference or memory corruption in case a device sends
data for an invalid port.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/serial/io_edgeport.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -1725,7 +1725,8 @@ static void edge_break(struct tty_struct
static void process_rcvd_data(struct edgeport_serial *edge_serial,
unsigned char *buffer, __u16 bufferLength)
{
- struct device *dev = &edge_serial->serial->dev->dev;
+ struct usb_serial *serial = edge_serial->serial;
+ struct device *dev = &serial->dev->dev;
struct usb_serial_port *port;
struct edgeport_port *edge_port;
__u16 lastBufferLength;
@@ -1821,9 +1822,8 @@ static void process_rcvd_data(struct edg

/* spit this data back into the tty driver if this
port is open */
- if (rxLen) {
- port = edge_serial->serial->port[
- edge_serial->rxPort];
+ if (rxLen && edge_serial->rxPort < serial->num_ports) {
+ port = serial->port[edge_serial->rxPort];
edge_port = usb_get_serial_port_data(port);
if (edge_port && edge_port->open) {
dev_dbg(dev, "%s - Sending %d bytes to TTY for port %d\n",
@@ -1833,8 +1833,8 @@ static void process_rcvd_data(struct edg
rxLen);
edge_port->port->icount.rx += rxLen;
}
- buffer += rxLen;
}
+ buffer += rxLen;
break;

case EXPECT_HDR3: /* Expect 3rd byte of status header */
@@ -1869,6 +1869,8 @@ static void process_rcvd_status(struct e
__u8 code = edge_serial->rxStatusCode;

/* switch the port pointer to the one being currently talked about */
+ if (edge_serial->rxPort >= edge_serial->serial->num_ports)
+ return;
port = edge_serial->serial->port[edge_serial->rxPort];
edge_port = usb_get_serial_port_data(port);
if (edge_port == NULL) {