1 files changed, 90 insertions, 13 deletions

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 9cf4069895c1..ff06c01a555b 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -550,11 +550,17 @@ struct ftdi_private {
         spinlock_t rx_lock;     /* spinlock for receive state */
         struct work_struct rx_work;
         int rx_processed;
+        unsigned long rx_bytes;
 
         __u16 interface;        /* FT2232C port interface (0 for FT232/245) */
 
         int force_baud;         /* if non-zero, force the baud rate to this value */
         int force_rtscts;       /* if non-zero, force RTS-CTS to always be enabled */
+
+        spinlock_t tx_lock;     /* spinlock for transmit state */
+        unsigned long tx_bytes;
+        unsigned long tx_outstanding_bytes;
+        unsigned long tx_outstanding_urbs;
 };
 
 /* Used for TIOCMIWAIT */
@@ -628,6 +634,9 @@ static struct usb_serial_driver ftdi_sio_device = {
 #define HIGH 1
 #define LOW 0
 
+/* number of outstanding urbs to prevent userspace DoS from happening */
+#define URB_UPPER_LIMIT 42
+
 /*
  * ***************************************************************************
  * Utlity functions
@@ -1158,6 +1167,7 @@ static int ftdi_sio_attach (struct usb_serial *serial)
         }
 
         spin_lock_init(&priv->rx_lock);
+        spin_lock_init(&priv->tx_lock);
         init_waitqueue_head(&priv->delta_msr_wait);
         /* This will push the characters through immediately rather
            than queue a task to deliver them */
@@ -1272,6 +1282,13 @@ static int  ftdi_open (struct usb_serial_port *port, struct file *filp)
 
         dbg("%s", __FUNCTION__);
 
+        spin_lock_irqsave(&priv->tx_lock, flags);
+        priv->tx_bytes = 0;
+        spin_unlock_irqrestore(&priv->tx_lock, flags);
+        spin_lock_irqsave(&priv->rx_lock, flags);
+        priv->rx_bytes = 0;
+        spin_unlock_irqrestore(&priv->rx_lock, flags);
+
         if (port->tty)
                 port->tty->low_latency = (priv->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
 
@@ -1374,6 +1391,7 @@ static int ftdi_write (struct usb_serial_port *port,
         int data_offset ;       /* will be 1 for the SIO and 0 otherwise */
         int status;
         int transfer_size;
+        unsigned long flags;
 
         dbg("%s port %d, %d bytes", __FUNCTION__, port->number, count);
 
@@ -1381,6 +1399,13 @@ static int ftdi_write (struct usb_serial_port *port,
                 dbg("write request of 0 bytes");
                 return 0;
         }
+        spin_lock_irqsave(&priv->tx_lock, flags);
+        if (priv->tx_outstanding_urbs > URB_UPPER_LIMIT) {
+                spin_unlock_irqrestore(&priv->tx_lock, flags);
+                dbg("%s - write limit hit\n", __FUNCTION__);
+                return 0;
+        }
+        spin_unlock_irqrestore(&priv->tx_lock, flags);
         
         data_offset = priv->write_offset;
         dbg("data_offset set to %d",data_offset);
@@ -1447,6 +1472,12 @@ static int ftdi_write (struct usb_serial_port *port,
                 err("%s - failed submitting write urb, error %d", __FUNCTION__, status);
                 count = status;
                 kfree (buffer);
+        } else {
+                spin_lock_irqsave(&priv->tx_lock, flags);
+                ++priv->tx_outstanding_urbs;
+                priv->tx_outstanding_bytes += count;
+                priv->tx_bytes += count;
+                spin_unlock_irqrestore(&priv->tx_lock, flags);
         }
 
         /* we are done with this urb, so let the host driver
@@ -1462,7 +1493,11 @@ static int ftdi_write (struct usb_serial_port *port,
 
 static void ftdi_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
 {
+        unsigned long flags;
         struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
+        struct ftdi_private *priv;
+        int data_offset;       /* will be 1 for the SIO and 0 otherwise */
+        unsigned long countback;
 
         /* free up the transfer buffer, as usb_free_urb() does not do this */
         kfree (urb->transfer_buffer);
@@ -1474,34 +1509,67 @@ static void ftdi_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
                 return;
         }
 
+        priv = usb_get_serial_port_data(port);
+        if (!priv) {
+                dbg("%s - bad port private data pointer - exiting", __FUNCTION__);
+                return;
+        }
+        /* account for transferred data */
+        countback = urb->actual_length;
+        data_offset = priv->write_offset;
+        if (data_offset > 0) {
+                /* Subtract the control bytes */
+                countback -= (data_offset * ((countback + (PKTSZ - 1)) / PKTSZ));
+        }
+        spin_lock_irqsave(&priv->tx_lock, flags);
+        --priv->tx_outstanding_urbs;
+        priv->tx_outstanding_bytes -= countback;
+        spin_unlock_irqrestore(&priv->tx_lock, flags);
+
         usb_serial_port_softint(port);
 } /* ftdi_write_bulk_callback */
 
 
 static int ftdi_write_room( struct usb_serial_port *port )
 {
+        struct ftdi_private *priv = usb_get_serial_port_data(port);
+        int room;
+        unsigned long flags;
+
         dbg("%s - port %d", __FUNCTION__, port->number);
 
-        /*
-         * We really can take anything the user throws at us
-         * but let's pick a nice big number to tell the tty
-         * layer that we have lots of free space
-         */
-        return 2048;
+        spin_lock_irqsave(&priv->tx_lock, flags);
+        if (priv->tx_outstanding_urbs < URB_UPPER_LIMIT) {
+                /*
+                 * We really can take anything the user throws at us
+                 * but let's pick a nice big number to tell the tty
+                 * layer that we have lots of free space
+                 */
+                room = 2048;
+        } else {
+                room = 0;
+        }
+        spin_unlock_irqrestore(&priv->tx_lock, flags);
+        return room;
 } /* ftdi_write_room */
 
 
 static int ftdi_chars_in_buffer (struct usb_serial_port *port)
 { /* ftdi_chars_in_buffer */
+        struct ftdi_private *priv = usb_get_serial_port_data(port);
+        int buffered;
+        unsigned long flags;
+
         dbg("%s - port %d", __FUNCTION__, port->number);
 
-        /* 
-         * We can't really account for how much data we
-         * have sent out, but hasn't made it through to the
-         * device, so just tell the tty layer that everything
-         * is flushed.
-         */
-        return 0;
+        spin_lock_irqsave(&priv->tx_lock, flags);
+        buffered = (int)priv->tx_outstanding_bytes;
+        spin_unlock_irqrestore(&priv->tx_lock, flags);
+        if (buffered < 0) {
+                err("%s outstanding tx bytes is negative!", __FUNCTION__);
+                buffered = 0;
+        }
+        return buffered;
 } /* ftdi_chars_in_buffer */
 
 
@@ -1511,6 +1579,8 @@ static void ftdi_read_bulk_callback (struct urb *urb, struct pt_regs *regs)
         struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
         struct tty_struct *tty;
         struct ftdi_private *priv;
+        unsigned long countread;
+        unsigned long flags;
 
         if (urb->number_of_packets > 0) {
                 err("%s transfer_buffer_length %d actual_length %d number of packets %d",__FUNCTION__,
@@ -1545,6 +1615,13 @@ static void ftdi_read_bulk_callback (struct urb *urb, struct pt_regs *regs)
                 return;
         }
 
+        /* count data bytes, but not status bytes */
+        countread = urb->actual_length;
+        countread -= 2 * ((countread + (PKTSZ - 1)) / PKTSZ);
+        spin_lock_irqsave(&priv->rx_lock, flags);
+        priv->rx_bytes += countread;
+        spin_unlock_irqrestore(&priv->rx_lock, flags);
+
         ftdi_process_read(port);
 
 } /* ftdi_read_bulk_callback */