linux-kernel - Re: [PATCH] spi: add null check before pointer dereference

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Date:   Tue, 23 May 2017 09:24:32 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     "Gustavo A. R. Silva" <garsilva@...eddedor.com>
Cc:     Kukjin Kim <kgene@...nel.org>, Andi Shyti <andi.shyti@...sung.com>,
        Mark Brown <broonie@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spi: add null check before pointer dereference

On Tue, May 23, 2017 at 2:25 AM, Gustavo A. R. Silva
<garsilva@...eddedor.com> wrote:
> Add null check before dereferencing pointer desc
>
> Addresses-Coverity-ID: 1397997
> Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
> ---
>  drivers/spi/spi-s3c64xx.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
> index b392cca..9f1013e 100644
> --- a/drivers/spi/spi-s3c64xx.c
> +++ b/drivers/spi/spi-s3c64xx.c
> @@ -306,6 +306,12 @@ static void prepare_dma(struct s3c64xx_spi_dma_data *dma,
>         desc = dmaengine_prep_slave_sg(dma->ch, sgt->sgl, sgt->nents,
>                                        dma->direction, DMA_PREP_INTERRUPT);
>
> +       if (!desc) {
> +               dev_err(&sdd->master->dev,
> +                       "%s:dmaengine_prep_slave_sg Failed\n", __func__);
> +               return;
> +       }

Although the check itself looks needed, but I think you did not handle
the error at all. You just bail out before submitting dma descriptor
but except that, everything else goes like there was no error. It
might work, might not... did you test this error path? How does it
behave?

Best regards,
Krzysztof