linux-kernel - Re: [PATCH] soc: mediatek: Handle return of of_match

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Message-ID: <CAMuHMdWxH9kQ7Zq5jCHL0hkA3Oin17f75TAq9dPC7FQMagT-vA@mail.gmail.com>
Date:   Thu, 1 Feb 2018 16:09:26 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Himanshu Jha <himanshujha199640@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Weiyi Lu <weiyi.lu@...iatek.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        sean.wang@...iatek.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        kevin-cw.chen@...iatek.com, Cheng Mars <mars.cheng@...iatek.com>,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] soc: mediatek: Handle return of of_match_device function

On Thu, Feb 1, 2018 at 4:02 PM, Robin Murphy <robin.murphy@....com> wrote:
> On 01/02/18 11:00, Himanshu Jha wrote:
>> In scpsys_probe function, return value of of_match_device function which
>> returns null is dereferenced without checking. Therefore, add a check for
>> potential null dereference.
>>
>> Detected by CoverityScan, CID#1424087 "Dereference null return value"
>>
>> Fixes: commit 53fddb1a66dd ("soc: mediatek: reduce code duplication of
>> scpsys_probe across all SoCs")
>> Signed-off-by: Himanshu Jha <himanshujha199640@...il.com>
>> ---
>>   drivers/soc/mediatek/mtk-scpsys.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/soc/mediatek/mtk-scpsys.c
>> b/drivers/soc/mediatek/mtk-scpsys.c
>> index 435ce5e..6e7f196 100644
>> --- a/drivers/soc/mediatek/mtk-scpsys.c
>> +++ b/drivers/soc/mediatek/mtk-scpsys.c
>> @@ -981,6 +981,9 @@ static int scpsys_probe(struct platform_device *pdev)
>>         int i, ret;
>>         match = of_match_device(of_scpsys_match_tbl, &pdev->dev);
>> +       if (!match)
>> +               return -EINVAL;
>> +
>>         soc = (const struct scp_soc_data *)match->data;
>
> You could of course replace the whole sequence with an
> of_device_get_match_data() call, which happens to be inherently safe against
> the no-match case even when that *is* impossible by design.

+1

>>         scp = init_scp(pdev, soc->domains, soc->num_domains, &soc->regs,

... followed by the static analyser gang complaining we may dereference
NULL pointer soc...

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