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Subject[PATCH] serial: access-after-NULL-check-at-uart_flush_buffer
From
Date
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.
This change applies to kernels from 2.6.16 till 2.6.25.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
drivers/serial/serial_core.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletion(-)

--- linux-2.6.25.orig/drivers/serial/serial_core.c
+++ linux-2.6.25/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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