linux-kernel - Re: [PATCH] mtd: gpmi: fix raw_buffer pointer double free issue

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Date:	Mon, 4 Apr 2016 23:31:16 +0200
From:	Richard Weinberger <richard@....at>
To:	Han Xu <han.xu@....com>, boris.brezillon@...e-electrons.com,
	dwmw2@...radead.org, computersforpeace@...il.com
Cc:	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: gpmi: fix raw_buffer pointer double free issue

Am 04.04.2016 um 22:41 schrieb Han Xu:
> fix the raw_buffer pointer double free issue found by coverify.
> 
> CID 18344 (#2 of 2): Double free (USE_AFTER_FREE)
> 3. double_free: Calling gpmi_alloc_dma_buffer frees pointer
> this->raw_buffer which has already been freed
> 
> Signed-off-by: Han Xu <han.xu@....com>
> ---
> 
> changes in v2:
>  - add coverity check log
> ---
>  drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> index 8122c69..dcb60b0 100644
> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> @@ -797,6 +797,7 @@ static void gpmi_free_dma_buffer(struct gpmi_nand_data *this)
>  
>  	this->cmd_buffer	= NULL;
>  	this->data_buffer_dma	= NULL;
> +	this->raw_buffer	= NULL;
>  	this->page_buffer_virt	= NULL;
>  	this->page_buffer_size	=  0;

Reviewed-by: Richard Weinberger <richard@....at>

Aside of that, the driver should IMHO be fixed to not call
gpmi_free_dma_buffer() multiple times on the same buffer...

Thanks,
//richard