linux-kernel - Re: [PATCH] kernel/resource.c: fix memory leak

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Message-ID: <alpine.LFD.2.00.1001090933040.7821@localhost.localdomain>
Date:	Sat, 9 Jan 2010 09:34:45 -0800 (PST)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Alexander Beregalov <a.beregalov@...il.com>
cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kernel/resource.c: fix memory leak



On Sat, 9 Jan 2010, Alexander Beregalov wrote:
>
> Free res before exit.
> Found by cppcheck.
> 
> Signed-off-by: Alexander Beregalov <a.beregalov@...il.com>
> ---
>  kernel/resource.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/resource.c b/kernel/resource.c
> index af96c1e..ae2e177 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -545,11 +545,12 @@ static void __init __reserve_region_with_split(struct resource *root,
>  	res->flags = IORESOURCE_BUSY;
>  
>  	conflict = __request_resource(parent, res);
> +	kfree(res);
> +
>  	if (!conflict)
>  		return;
>  
>  	/* failed, split and try again */
> -	kfree(res);

As Amerigo pointed out, this is very wrong indeed.

If we don't have a conflict, then __request_resource() will have inserted 
the resource into the resource tree, and we absolutely must _not_ free it.

So that cppcheck tool is way too simplistic, and wrong.

			Linus
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