From ian.abbott@mev.co.uk Mon Jun 26 03:44:29 2006 Message-ID: <449FBA86.5070800@mev.co.uk> Date: Mon, 26 Jun 2006 11:44:22 +0100 From: Ian Abbott Cc: Greg KH Subject: USB serial visor: fix race in open/close From: Ian Abbott The anti user-DoS mechanism in the USB serial 'visor' driver can fail in the following way: visor_open: priv->outstanding_urbs = 0 visor_write: ++priv->outstanding_urbs visor_close: visor_open: priv->outstanding_urbs = 0 visor_write_bulk_callback: --priv->outstanding_urbs So priv->outstanding_urbs ends up as (unsigned long)(-1). Not good! I haven't seen this happen with the visor driver as I don't have the hardware, but I have seen it while testing a patch to implement the same functionality in the ftdi_sio driver (patch not yet submitted). The fix is pretty simple: don't reinitialize outstanding_urbs in visor_open. (Again, I haven't tested the fix in visor, but I have tested it in ftdi_sio.) Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/visor.c | 1 - 1 file changed, 1 deletion(-) --- gregkh-2.6.orig/drivers/usb/serial/visor.c +++ gregkh-2.6/drivers/usb/serial/visor.c @@ -302,7 +302,6 @@ static int visor_open (struct usb_serial spin_lock_irqsave(&priv->lock, flags); priv->bytes_in = 0; priv->bytes_out = 0; - priv->outstanding_urbs = 0; priv->throttled = 0; spin_unlock_irqrestore(&priv->lock, flags);