linux-kernel - Re: [PATCH] dmaengine: do not allow access outside of unmap

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Date:	Tue, 7 Jun 2016 11:35:20 +0530
From:	Vinod Koul <vinod.koul@...el.com>
To:	Colin King <colin.king@...onical.com>
Cc:	Dan Williams <dan.j.williams@...el.com>, dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: do not allow access outside of unmap_pool

On Tue, May 17, 2016 at 01:00:46PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> When CONFIG_DMA_ENGINE_RAID is defined, unmap_pool[] is just 1
> element in size, however, allows orders of 2..8 to access
> outside unmap_pool and returns an invalid address. Ensure
> we fall into the default path and report a BUG() when
> CONFIG_DMA_ENGINE_RAID is defined and order is out of range.
> 
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/dma/dmaengine.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 8c9f45f..6027e66 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -1100,12 +1100,14 @@ static struct dmaengine_unmap_pool *__get_unmap_pool(int nr)
>  	switch (order) {
>  	case 0 ... 1:
>  		return &unmap_pool[0];
> +	#if IS_ENABLED(CONFIG_DMA_ENGINE_RAID)

Okay if CONFIG_DMA_ENGINE_RAID is enabled (m or y) then IS_ENABLED
return 1, so we will go inside and not fall into default. And I though
by changelog that you want it to go to default in CONFIG_DMA_ENGINE_RAID
is defined!

What did I miss...

>  	case 2 ... 4:
>  		return &unmap_pool[1];
>  	case 5 ... 7:
>  		return &unmap_pool[2];
>  	case 8:
>  		return &unmap_pool[3];
> +	#endif
>  	default:
>  		BUG();
>  		return NULL;
> -- 
> 2.8.1
> 

-- 
~Vinod