Re: [PATCH] soc: mediatek: Handle return of of_match_device function

[Robin Murphy]

On 01/02/18 15:09, Geert Uytterhoeven wrote:
> On Thu, Feb 1, 2018 at 4:02 PM, Robin Murphy <robin.murphy@xxxxxxx> 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@xxxxxxxxx>
> > > ---
> > >    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...

Well, if the static analysers can't track the provenance of 
dev->driver->of_match_table, let's keep ignoring them until they get 
cleverer :P

Robin.

> Gr{oetje,eeting}s,
>
>                          Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> 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