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DateSun, 27 Apr 2008 12:46:22 +0200 (CEST)
FromJulia Lawall <>
Subject[PATCH] drivers/video/pnx4008: eliminate double free
From: 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/)

// <smpl>
@@
expression E;
@@

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

@@
expression E;
@@

* framebuffer_release(E);
...
* kfree(E);
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
---
diff -u -p a/drivers/video/pnx4008/pnxrgbfb.c b/drivers/video/pnx4008/pnxrgbfb.c
--- a/drivers/video/pnx4008/pnxrgbfb.c 2008-04-07 13:50:27.000000000 +0200
+++ b/drivers/video/pnx4008/pnxrgbfb.c 2008-04-27 12:25:52.000000000 +0200
@@ -100,7 +100,6 @@ static int rgbfb_remove(struct platform_
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

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;
}

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