linux-kernel - Re: [PATCH 2/2] fs/ext4: Eliminate double free

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Message-ID: <20091223125334.GE21594@thunk.org>
Date:	Wed, 23 Dec 2009 07:53:34 -0500
From:	tytso@....edu
To:	Julia Lawall <julia@...u.dk>
Cc:	Andreas Dilger <adilger@....com>, linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 2/2] fs/ext4: Eliminate double free

On Sun, Dec 20, 2009 at 06:07:10PM +0100, Julia Lawall wrote:
> From: Julia Lawall <julia@...u.dk>
> 
> b_entry_name and buffer are initially NULL, are initialized within a loop
> to the result of calling kmalloc, and are freed at the bottom of this loop.
> The loop contains gotos to cleanup, which also frees b_entry_name and
> buffer.  Some of these gotos are before the reinitializations of
> b_entry_name and buffer.  To maintain the invariant that b_entry_name and
> buffer are NULL at the top of the loop, and thus acceptable arguments to
> kfree, these variables are now set to NULL after the kfrees.
> 
> This seems to be the simplest solution.  A more complicated solution
> would be to introduce more labels in the error handling code at the end of
> the function.

Thanks, added to the ext4 patch queue.

						- Ted
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