drivers/video/pnx4008: eliminate double free

Author: Julia Lawall <julia@diku.dk>

The function framebuffer_release just calls kfree, so calling kfree
subsequently on the same argument represents a double free.  The comments with
the definition of framebuffer_release in drivers/video/fbsysfs.c suggest that
a more elaborate definition of this function is planned, such that the
splitting up of framebuffer_release and kfree as done in the second instance
might someday make sense, but it does not make sense now.

This was found using the following semantic match.
(http://www.emn.fr/x-info/coccinelle/)

// 
@@
expression E;
@@

* kfree(E);
...
* framebuffer_release(E);

@@
expression E;
@@

* framebuffer_release(E);
...
* kfree(E);
// 

Signed-off-by: Julia Lawall 
Cc: Vitaly Wool 
Cc: Krzysztof Helt 
Cc: Grigory Tolstolytkin 
Cc: Antonino Daplas 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

---
 drivers/video/pnx4008/pnxrgbfb.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)
 
diff --git a/drivers/video/pnx4008/pnxrgbfb.c b/drivers/video/pnx4008/pnxrgbfb.c
index 685761a..4db6b48 100644
--- a/drivers/video/pnx4008/pnxrgbfb.c
+++ b/drivers/video/pnx4008/pnxrgbfb.c
@@ -100,7 +100,6 @@ static int rgbfb_remove(struct platform_device *pdev)
 		fb_dealloc_cmap(&info->cmap);
 		framebuffer_release(info);
 		platform_set_drvdata(pdev, NULL);
-		kfree(info);
 	}
 
 	pnx4008_free_dum_channel(channel_owned, pdev->id);
@@ -168,23 +167,21 @@ static int __devinit rgbfb_probe(struct platform_device *pdev)
 
 	ret = fb_alloc_cmap(&info->cmap, 256, 0);
 	if (ret < 0)
-		goto err2;
+		goto err1;
 
 	ret = register_framebuffer(info);
 	if (ret < 0)
-		goto err3;
+		goto err2;
 	platform_set_drvdata(pdev, info);
 
 	return 0;
 
-err3:
-	fb_dealloc_cmap(&info->cmap);
 err2:
-	framebuffer_release(info);
+	fb_dealloc_cmap(&info->cmap);
 err1:
 	pnx4008_free_dum_channel(channel_owned, pdev->id);
 err0:
-	kfree(info);
+	framebuffer_release(info);
 err:
 	return ret;
 }

drivers/video/pnx4008: eliminate double free

qlambert

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