linux-kernel - [PATCH v2] drm/gma500: fix double freeing

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Message-Id: <1444146539-5698-1-git-send-email-sudipm.mukherjee@gmail.com>
Date:	Tue,  6 Oct 2015 21:18:59 +0530
From:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:	David Airlie <airlied@...ux.ie>
Cc:	linux-kernel@...r.kernel.org,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	dri-devel@...ts.freedesktop.org,
	Sudip Mukherjee <sudipm.mukherjee@...il.com>,
	Patrik Jakobsson <patrik.r.jakobsson@...il.com>
Subject: [PATCH v2] drm/gma500: fix double freeing

We are allocating backing using psbfb_alloc() and so
backing->stolen is always true. So we were freeing backing two times.
Moreover if we follow the execution path then we should be freeing
backing after we have released the helper. So remove the one which frees
backing before the helper is released.
While at it the error labels are also renamed to give a meaningful
name.

Cc: Patrik Jakobsson <patrik.r.jakobsson@...il.com>
Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
---

Hi Patrik,
If you donot like the labels I will change them according to what you
have suggested.   

 drivers/gpu/drm/gma500/framebuffer.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c
index 2eaf1b3..52e2bf3 100644
--- a/drivers/gpu/drm/gma500/framebuffer.c
+++ b/drivers/gpu/drm/gma500/framebuffer.c
@@ -411,7 +411,7 @@ static int psbfb_create(struct psb_fbdev *fbdev,
 	info = drm_fb_helper_alloc_fbi(&fbdev->psb_fb_helper);
 	if (IS_ERR(info)) {
 		ret = PTR_ERR(info);
-		goto out_err1;
+		goto err_alloc_fbi;
 	}
 	info->par = fbdev;
 
@@ -419,7 +419,7 @@ static int psbfb_create(struct psb_fbdev *fbdev,
 
 	ret = psb_framebuffer_init(dev, psbfb, &mode_cmd, backing);
 	if (ret)
-		goto out_unref;
+		goto err_framebuffer_init;
 
 	fb = &psbfb->base;
 	psbfb->fbdev = info;
@@ -465,14 +465,9 @@ static int psbfb_create(struct psb_fbdev *fbdev,
 
 	mutex_unlock(&dev->struct_mutex);
 	return 0;
-out_unref:
-	if (backing->stolen)
-		psb_gtt_free_range(dev, backing);
-	else
-		drm_gem_object_unreference(&backing->gem);
-
+err_framebuffer_init:
 	drm_fb_helper_release_fbi(&fbdev->psb_fb_helper);
-out_err1:
+err_alloc_fbi:
 	mutex_unlock(&dev->struct_mutex);
 	psb_gtt_free_range(dev, backing);
 	return ret;
-- 
1.9.1

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