linux-kernel - [PATCH 3/4] tty/serial: at91: prevent null dereference in tasklet function

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Date:	Tue, 7 Jan 2014 11:45:08 +0100
From:	Nicolas Ferre <nicolas.ferre@...el.com>
To:	<gregkh@...uxfoundation.org>
CC:	Leilei Zhao <leilei.zhao@...el.com>, <mark.roszko@...il.com>,
	<mdeneen@...il.com>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-serial@...r.kernel.org>,
	<stable@...r.kernel.org>, Nicolas Ferre <nicolas.ferre@...el.com>
Subject: [PATCH 3/4] tty/serial: at91: prevent null dereference in tasklet function

From: Marek Roszko <mark.roszko@...il.com>

Something asks a tasklet to be scheduled when the uart port is closed.
Need to supress the kernel panic for now by checking if the port is NULL or
not.

Signed-off-by: Marek Roszko <mark.roszko@...il.com>
Acked-by: Leilei Zhao <leilei.zhao@...el.com>
Cc: <stable@...r.kernel.org> # v3.12
Signed-off-by: Nicolas Ferre <nicolas.ferre@...el.com>
---
 drivers/tty/serial/atmel_serial.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index c421d11b3d4c..6e68486c83cb 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1360,6 +1360,10 @@ static void atmel_tasklet_func(unsigned long data)
 	unsigned int status;
 	unsigned int status_change;
 
+	if(!port->state || !port->state->port.tty)
+		/* uart has been closed */
+		return;
+
 	/* The interrupt handler does not take the lock */
 	spin_lock(&port->lock);
 
-- 
1.8.2.2

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