linux-kernel - [PATCH] intel, gma500, lvds: Fix use after free and mem leak in psb_intel_lvds

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Message-ID: <alpine.LNX.2.00.1201142211370.11547@swampdragon.chaosbits.net>
Date:	Sat, 14 Jan 2012 22:15:55 +0100 (CET)
From:	Jesper Juhl <jj@...osbits.net>
To:	linux-kernel@...r.kernel.org
cc:	dri-devel@...ts.freedesktop.org,
	Octavian Purdila <octavian.purdila@...el.com>,
	Dave Airlie <airlied@...hat.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Alan Cox <alan@...ux.intel.com>,
	David Airlie <airlied@...ux.ie>, Eric Anholt <eric@...olt.net>,
	Jesse Barnes <jesse.barnes@...el.com>
Subject: [PATCH] intel, gma500, lvds: Fix use after free and mem leak in
 psb_intel_lvds_init()

In psb_intel_lvds_init(), if we fail to allocate memory for
'psb_intel_connector' we free the memory we previously allocated for
'psb_intel_encoder', but we then proceed to use that free'd pointer
when we do 'psb_intel_encoder->dev_priv = lvds_priv;'.

We may also leak the memory we allocated for 'psb_intel_encoder' if we 
'goto failed_connector;' and the variable goes out of scope.

While I was there anyway, I also removed the pointless 'if
(psb_intel_connector)' before freeing it at the 'failed_connector:'
label - kfree() deals gracefully with NULL pointers, so it is not
needed.

Signed-off-by: Jesper Juhl <jj@...osbits.net>
---
 drivers/gpu/drm/gma500/psb_intel_lvds.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/gma500/psb_intel_lvds.c b/drivers/gpu/drm/gma500/psb_intel_lvds.c
index a25e4ca..0a43758 100644
--- a/drivers/gpu/drm/gma500/psb_intel_lvds.c
+++ b/drivers/gpu/drm/gma500/psb_intel_lvds.c
@@ -713,7 +713,6 @@ void psb_intel_lvds_init(struct drm_device *dev,
 
 	psb_intel_encoder =
 			kzalloc(sizeof(struct psb_intel_encoder), GFP_KERNEL);
-
 	if (!psb_intel_encoder) {
 		dev_err(dev->dev, "psb_intel_encoder allocation error\n");
 		return;
@@ -721,10 +720,9 @@ void psb_intel_lvds_init(struct drm_device *dev,
 
 	psb_intel_connector =
 		kzalloc(sizeof(struct psb_intel_connector), GFP_KERNEL);
-
 	if (!psb_intel_connector) {
-		kfree(psb_intel_encoder);
 		dev_err(dev->dev, "psb_intel_connector allocation error\n");
+		goto failed_encoder;
 	}
 
 	lvds_priv = kzalloc(sizeof(struct psb_intel_lvds_priv), GFP_KERNEL);
@@ -862,7 +860,8 @@ failed_blc_i2c:
 	drm_encoder_cleanup(encoder);
 	drm_connector_cleanup(connector);
 failed_connector:
-	if (psb_intel_connector)
-		kfree(psb_intel_connector);
+	kfree(psb_intel_connector);
+failed_encoder:
+	kfree(psb_intel_encoder);
 }
 
-- 
1.7.8.3


-- 
Jesper Juhl <jj@...osbits.net>       http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
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