linux-kernel - Re: [BUG][PATCH]dma-coherent.c: error path bug

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Message-Id: <20100607113001S.fujita.tomonori@lab.ntt.co.jp>
Date:	Mon, 7 Jun 2010 11:30:48 +0900
From:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To:	mitov@...p.bas.bg
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [BUG][PATCH]dma-coherent.c: error path bug

On Sun, 6 Jun 2010 13:53:04 +0300
Marin Mitov <mitov@...p.bas.bg> wrote:

> Hi all,
> 
> The error path in dma_declare_coherent_memory() leaves 
> the pointer dev->dma_mem non completely initialized.
> 
> If allocation of dev->dma_mem succeeds, 
> but allocation of dev->dma_mem->bitmap fails
> dev->dma_mem is freed, but left non NULL
> and non completely initialized.
> 
> Either zero it after being freed (one liner patch), or assign to 
> dev->dma_mem only completely initialized structure (patch included).
> 
> Comments welcome.
> 
> Marin Mitov
> 
> Signed-off-by: Marin Mitov <mitov@...p.bas.bg>

Hmm, if dma_declare_coherent_memory() fails, the driver doesn't use
dev->dma_mem. So even if dev->dma_mem points to a freed memory, I'm
not sure that it causes a real problem. We could call this patch a
cleanup though.
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