USB: serial: digi_acceleport: fix incomplete rx sanity check

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@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 23 insertions, 15 deletions

diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c
index 30bf0f5db82d..7ab3235febfc 100644
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -1398,25 +1398,30 @@ static int digi_read_inb_callback(struct urb *urb)
 {
         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;
         }
 
@@ -1430,6 +1435,9 @@ static int digi_read_inb_callback(struct urb *urb)
 
         /* receive data */
         if (opcode == DIGI_CMD_RECEIVE_DATA) {
+                port_status = buf[2];
+                data = &buf[3];
+
                 /* get flag from port_status */
                 flag = 0;