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

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Message-ID: <CAMuHMdVNTT9JJvZ_SuSUkAPMqYOmdG-4zLggwaT_ObStbGG_ow@mail.gmail.com>
Date:   Tue, 23 May 2017 09:33:25 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     "Gustavo A. R. Silva" <garsilva@...eddedor.com>,
        Kukjin Kim <kgene@...nel.org>,
        Andi Shyti <andi.shyti@...sung.com>,
        Mark Brown <broonie@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] spi: add null check before pointer dereference

On Tue, May 23, 2017 at 9:24 AM, Krzysztof Kozlowski <krzk@...nel.org> wrote:
> 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?

I.e. does it fall back to PIO?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds