Subject: [PATCH] pxa2xx_spi: fix memory corruption

From: [email-masked] (Marek Vasut)
Date: Sun, 10 Jul 2011 01:05:48 +0200

On Saturday, July 09, 2011 11:14:58 PM Vasily Khoruzhick wrote:
> pxa2xx_spi_probe allocates struct driver_data and null_dma_buf
> at same time via spi_alloc_master(), but then calculates
> null_dma_buf pointer incorrectly, and it causes memory corruption
> later if DMA usage is enabled.
> 
> Signed-off-by: Vasily Khoruzhick <[email-masked]>
> ---
>  drivers/spi/pxa2xx_spi.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c
> index dc25bee..ef38fbf 100644
> --- a/drivers/spi/pxa2xx_spi.c
> +++ b/drivers/spi/pxa2xx_spi.c
> @@ -1569,7 +1569,7 @@ static int __devinit pxa2xx_spi_probe(struct
> platform_device *pdev) master->transfer = transfer;
> 
>  	drv_data->ssp_type = ssp->type;
> -	drv_data->null_dma_buf = (u32 *)ALIGN((u32)(drv_data +
> +	drv_data->null_dma_buf = (u32 *)ALIGN(((u32)drv_data +
>  						sizeof(struct driver_data)), 8);

This thing looks a bit disturbing in itself. Like, where the heck is that thing 
pointing in the end ? Since some data are written to address in "null_dma_buf" 
... isn't this just changing the corruption impact ?
> 
>  	drv_data->ioaddr = ssp->mmio_base;