[patch 03/37] serial: access after NULL check inuart_flush_buffer()

[Greg KH]

2.6.25-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>

commit 55d7b68996a5064f011d681bca412b6281d2f711 upstream

I noticed that

  static void uart_flush_buffer(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *port = state->port;
  	unsigned long flags;

  	/*
  	 * This means you called this function _after_ the port was
  	 * closed.  No cookie for you.
  	 */
  	if (!state || !state->info) {
  		WARN_ON(1);
  		return;
  	}

is too late for checking state != NULL.

Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/serial/serial_core.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -535,7 +535,7 @@ static int uart_chars_in_buffer(struct t
 static void uart_flush_buffer(struct tty_struct *tty)
 {
 	struct uart_state *state = tty->driver_data;
-	struct uart_port *port = state->port;
+	struct uart_port *port;
 	unsigned long flags;
 
 	/*
@@ -547,6 +547,7 @@ static void uart_flush_buffer(struct tty
 		return;
 	}
 
+	port = state->port;
 	pr_debug("uart_flush_buffer(%d) called\n", tty->index);
 
 	spin_lock_irqsave(&port->lock, flags);

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