[PATCH 4.4 29/60] USB: serial: digi_acceleport: fix incomplete rx sanity check

From: Greg Kroah-Hartman
Date: Thu May 11 2017 - 10:30:11 EST


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

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

From: Johan Hovold <johan@xxxxxxxxxx>

commit 1b0aed2b1600f6e5c7b9acfbd610a4e351ef5232 upstream.

Make sure the received data has the required headers before parsing it.

Also drop the redundant urb-status check, which has already been handled
by the caller.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/usb/serial/digi_acceleport.c | 38 +++++++++++++++++++++--------------
1 file changed, 23 insertions(+), 15 deletions(-)

--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -1399,25 +1399,30 @@ static int digi_read_inb_callback(struct
{
struct usb_serial_port *port = urb->context;
struct digi_port *priv = usb_get_serial_port_data(port);
- int opcode = ((unsigned char *)urb->transfer_buffer)[0];
- int len = ((unsigned char *)urb->transfer_buffer)[1];
- int port_status = ((unsigned char *)urb->transfer_buffer)[2];
- unsigned char *data = ((unsigned char *)urb->transfer_buffer) + 3;
+ unsigned char *buf = urb->transfer_buffer;
+ int opcode;
+ int len;
+ int port_status;
+ unsigned char *data;
int flag, throttled;
- int status = urb->status;
-
- /* do not process callbacks on closed ports */
- /* but do continue the read chain */
- if (urb->status == -ENOENT)
- return 0;

/* short/multiple packet check */
+ if (urb->actual_length < 2) {
+ dev_warn(&port->dev, "short packet received\n");
+ return -1;
+ }
+
+ opcode = buf[0];
+ len = buf[1];
+
if (urb->actual_length != len + 2) {
- dev_err(&port->dev, "%s: INCOMPLETE OR MULTIPLE PACKET, "
- "status=%d, port=%d, opcode=%d, len=%d, "
- "actual_length=%d, status=%d\n", __func__, status,
- priv->dp_port_num, opcode, len, urb->actual_length,
- port_status);
+ dev_err(&port->dev, "malformed packet received: port=%d, opcode=%d, len=%d, actual_length=%u\n",
+ priv->dp_port_num, opcode, len, urb->actual_length);
+ return -1;
+ }
+
+ if (opcode == DIGI_CMD_RECEIVE_DATA && len < 1) {
+ dev_err(&port->dev, "malformed data packet received\n");
return -1;
}

@@ -1431,6 +1436,9 @@ static int digi_read_inb_callback(struct

/* receive data */
if (opcode == DIGI_CMD_RECEIVE_DATA) {
+ port_status = buf[2];
+ data = &buf[3];
+
/* get flag from port_status */
flag = 0;