linux-kernel - [PATCH 1/1] NET: irda, fix potential null dereference

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Message-Id: <1263114674-10433-1-git-send-email-jslaby@suse.cz>
Date:	Sun, 10 Jan 2010 10:11:14 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	samuel@...tiz.org
Cc:	linux-kernel@...r.kernel.org, jirislaby@...il.com,
	"David S. Miller" <davem@...emloft.net>,
	Alan Cox <alan@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...e.de>, netdev@...r.kernel.org
Subject: [PATCH 1/1] NET: irda, fix potential null dereference

Stanse found a potential null dereference in ircomm_tty_close
and ircomm_tty_hangup. There is a check for tty being NULL,
but it is dereferenced earlier. Move the dereference after
the check.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Cc: Samuel Ortiz <samuel@...tiz.org>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Alan Cox <alan@...ux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@...e.de>
Cc: netdev@...r.kernel.org
---
 net/irda/ircomm/ircomm_tty.c |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/net/irda/ircomm/ircomm_tty.c b/net/irda/ircomm/ircomm_tty.c
index 811984d..42a7d75 100644
--- a/net/irda/ircomm/ircomm_tty.c
+++ b/net/irda/ircomm/ircomm_tty.c
@@ -491,7 +491,7 @@ static int ircomm_tty_open(struct tty_struct *tty, struct file *filp)
  */
 static void ircomm_tty_close(struct tty_struct *tty, struct file *filp)
 {
-	struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;
+	struct ircomm_tty_cb *self;
 	unsigned long flags;
 
 	IRDA_DEBUG(0, "%s()\n", __func__ );
@@ -499,6 +499,8 @@ static void ircomm_tty_close(struct tty_struct *tty, struct file *filp)
 	if (!tty)
 		return;
 
+	self = tty->driver_data;
+
 	IRDA_ASSERT(self != NULL, return;);
 	IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);
 
@@ -999,17 +1001,19 @@ static void ircomm_tty_shutdown(struct ircomm_tty_cb *self)
  */
 static void ircomm_tty_hangup(struct tty_struct *tty)
 {
-	struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;
+	struct ircomm_tty_cb *self;
 	unsigned long	flags;
 
 	IRDA_DEBUG(0, "%s()\n", __func__ );
 
-	IRDA_ASSERT(self != NULL, return;);
-	IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);
-
 	if (!tty)
 		return;
 
+	self = tty->driver_data;
+
+	IRDA_ASSERT(self != NULL, return;);
+	IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);
+
 	/* ircomm_tty_flush_buffer(tty); */
 	ircomm_tty_shutdown(self);
 
-- 
1.6.5.7

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