linux-kernel - [PATCH] double-free security PTI fix

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Date:	Wed, 25 May 2011 14:38:18 -0700
From:	james_p_freyensee@...ux.intel.com
To:	gregkh@...e.de
Cc:	linux-kernel@...r.kernel.org, christophe.guerard@...el.com,
	james_p_freyensee@...ux.intel.com, rocher.jeremy@...il.com
Subject: [PATCH] double-free security PTI fix

From: J Freyensee <james_p_freyensee@...ux.intel.com>

This patch fixes a double-free error that will not always be
seen unless /dev/pti char interface is stressed.

Signed-off-by: J Freyensee <james_p_freyensee@...ux.intel.com>
---
 drivers/misc/pti.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/pti.c b/drivers/misc/pti.c
index bb6f925..be48573 100644
--- a/drivers/misc/pti.c
+++ b/drivers/misc/pti.c
@@ -317,7 +317,8 @@ EXPORT_SYMBOL_GPL(pti_request_masterchannel);
  *				a master, channel ID address
  *				used to write to PTI HW.
  *
- * @mc: master, channel apeture ID address to be released.
+ * @mc: master, channel apeture ID address to be released.  This
+ *      will de-allocate the structure via kfree().
  */
 void pti_release_masterchannel(struct pti_masterchannel *mc)
 {
@@ -581,7 +582,7 @@ static int pti_char_open(struct inode *inode, struct file *filp)
 static int pti_char_release(struct inode *inode, struct file *filp)
 {
 	pti_release_masterchannel(filp->private_data);
-	kfree(filp->private_data);
+	filp->private_data = NULL;
 	return 0;
 }
 
-- 
1.7.2.3

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