linux-kernel - [PATCH 1/2] serial: fix NULL pointer dereference

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Date:	Sun, 25 Oct 2009 11:16:32 -0200
From:	André Goddard Rosa <andre.goddard@...il.com>
To:	gregkh@...e.de, alan@...ux.intel.com,
	Andrew Morton <akpm@...ux-foundation.org>, adobriyan@...il.com,
	linux list <linux-kernel@...r.kernel.org>
Cc:	me <andre.goddard@...il.com>
Subject: [PATCH 1/2] serial: fix NULL pointer dereference

>From f90016f1d9186ba44da028201a984735fc9a6672 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Goddard=20Rosa?= <andre.goddard@...il.com>
Date: Sat, 24 Oct 2009 11:04:25 -0200
Subject: [PATCH 1/2] serial: fix NULL pointer dereference
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

If kzalloc() or alloc_tty_driver() fails, we call:
    put_tty_driver(normal = NULL).

Then:
    put_tty_driver -> tty_driver_kref_put -> kref_put(&NULL->kref, ...)

Signed-off-by: André Goddard Rosa <andre.goddard@...il.com>

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index dcc7244..885eabe 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -2344,7 +2344,7 @@ static const struct tty_operations uart_ops = {
  */
 int uart_register_driver(struct uart_driver *drv)
 {
-	struct tty_driver *normal = NULL;
+	struct tty_driver *normal;
 	int i, retval;

 	BUG_ON(drv->state);
@@ -2354,13 +2354,12 @@ int uart_register_driver(struct uart_driver *drv)
 	 * we have a large number of ports to handle.
 	 */
 	drv->state = kzalloc(sizeof(struct uart_state) * drv->nr, GFP_KERNEL);
-	retval = -ENOMEM;
 	if (!drv->state)
 		goto out;

-	normal  = alloc_tty_driver(drv->nr);
+	normal = alloc_tty_driver(drv->nr);
 	if (!normal)
-		goto out;
+		goto out_kfree;

 	drv->tty_driver = normal;

@@ -2393,12 +2392,14 @@ int uart_register_driver(struct uart_driver *drv)
 	}

 	retval = tty_register_driver(normal);
- out:
-	if (retval < 0) {
-		put_tty_driver(normal);
-		kfree(drv->state);
-	}
-	return retval;
+	if (retval >= 0)
+		return retval;
+
+	put_tty_driver(normal);
+out_kfree:
+	kfree(drv->state);
+out:
+	return -ENOMEM;
 }

 /**
-- 
1.6.5.1.75.g02d56
--
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