linux-kernel - Re: [PATCH v2] mmc: omap: Initialize dma_slave_config to avoid random data in it's fields

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Message-ID: <CAPDyKFpaj3qd1GYXhvp_EeoHEu63NrPB_L7GddkS7WCGs1ME_g@mail.gmail.com>
Date:   Wed, 14 Sep 2016 14:01:43 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Peter Ujfalusi <peter.ujfalusi@...com>
Cc:     Arnd Bergmann <arnd@...db.de>, Tony Lindgren <tony@...mide.com>,
        Kishon <kishon@...com>, linux-omap <linux-omap@...r.kernel.org>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mmc: omap: Initialize dma_slave_config to avoid random
 data in it's fields

On 14 September 2016 at 13:21, Peter Ujfalusi <peter.ujfalusi@...com> wrote:
> It is wrong to use uninitialized dma_slave_config and configure only
> certain fields as the DMAengine driver might look at non initialized
> (random data) fields and tries to interpret it.
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>

Thanks, applied for fixes!

Kind regards
Uffe

> ---
> Hi,
>
> Changes since v1:
> - do the field initialization in one step
>
> would it be possible to send this patch for 4.8? I have omap-dma DMAengine
> driver changes pending, but they break the MMC/SD because of the uninitialized
> fields in dma_slave_config.
>
> Thanks,
> Peter
>
>  drivers/mmc/host/omap.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mmc/host/omap.c b/drivers/mmc/host/omap.c
> index f23d65eb070d..be3c49fa7382 100644
> --- a/drivers/mmc/host/omap.c
> +++ b/drivers/mmc/host/omap.c
> @@ -1016,14 +1016,16 @@ mmc_omap_prepare_data(struct mmc_omap_host *host, struct mmc_request *req)
>
>                 /* Only reconfigure if we have a different burst size */
>                 if (*bp != burst) {
> -                       struct dma_slave_config cfg;
> -
> -                       cfg.src_addr = host->phys_base + OMAP_MMC_REG(host, DATA);
> -                       cfg.dst_addr = host->phys_base + OMAP_MMC_REG(host, DATA);
> -                       cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
> -                       cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
> -                       cfg.src_maxburst = burst;
> -                       cfg.dst_maxburst = burst;
> +                       struct dma_slave_config cfg = {
> +                               .src_addr = host->phys_base +
> +                                           OMAP_MMC_REG(host, DATA),
> +                               .dst_addr = host->phys_base +
> +                                           OMAP_MMC_REG(host, DATA),
> +                               .src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES,
> +                               .dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES,
> +                               .src_maxburst = burst,
> +                               .dst_maxburst = burst,
> +                       };
>
>                         if (dmaengine_slave_config(c, &cfg))
>                                 goto use_pio;
> --
> 2.10.0
>