From: Johan Hovold <johan@kernel.org> commit e7b931bee739e8a77ae216e613d3b99342b6dec0 upstream. The driver would happily overwrite its write buffer with user data in 256 byte increments due to a removed buffer-space sanity check. Fixes: 5fcf62b0f1f2 ("tty: iuu_phoenix: fix locking.") Cc: stable <stable@vger.kernel.org> # 2.6.31 Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/usb/serial/iuu_phoenix.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/usb/serial/iuu_phoenix.c b/drivers/usb/serial/iuu_phoenix.c index 449e89db9cea..e287fd52c575 100644 --- a/drivers/usb/serial/iuu_phoenix.c +++ b/drivers/usb/serial/iuu_phoenix.c @@ -697,14 +697,16 @@ static int iuu_uart_write(struct tty_struct *tty, struct usb_serial_port *port, struct iuu_private *priv = usb_get_serial_port_data(port); unsigned long flags; - if (count > 256) - return -ENOMEM; - spin_lock_irqsave(&priv->lock, flags); + count = min(count, 256 - priv->writelen); + if (count == 0) + goto out; + /* fill the buffer */ memcpy(priv->writebuf + priv->writelen, buf, count); priv->writelen += count; +out: spin_unlock_irqrestore(&priv->lock, flags); return count; -- 2.25.1