linux-kernel - Re: [PATCH][next] pinctrl: th1520: Dereference pointer only after NULL check

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Message-ID: <CAEO-vhFkT6RwR6h7KRD0YyQphhuqm0d53xj7xp7r3gco+DxwHg@mail.gmail.com>
Date: Wed, 16 Oct 2024 20:54:17 -0600
From: "Everest K.C." <everestkc@...restkc.com.np>
To: Shuah Khan <skhan@...uxfoundation.org>
Cc: drew@...7.com, guoren@...nel.org, wefu@...hat.com, 
	linus.walleij@...aro.org, linux-riscv@...ts.infradead.org, 
	linux-gpio@...r.kernel.org, kernel-janitors@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] pinctrl: th1520: Dereference pointer only after
 NULL check

On Wed, Oct 16, 2024 at 3:00 PM Shuah Khan <skhan@...uxfoundation.org> wrote:
>
> On 10/16/24 07:42, Everest K.C. wrote:
> > The pointer `func` is dereferenced before NULL check.
> > Move the dereference after the NULL check.
>
> Change log looks fine.
>
> Short log that clearly says it is a fix would be better:
>
> Fix potential null pointer defereference
>
> >
> > This issue was reported by Coverity Scan.
> > Report:
> > CID 1600802: (#1 of 1): Dereference before null check
> > (REVERSE_INULL)
> > check_after_deref: Null-checking func suggests that it
> > may be null, but it has already been dereferenced on all
> > paths leading to the check.
> >
> > Fixes: 1fc30cd92770 ("pinctrl: th1520: Factor out casts")
> > Signed-off-by: Everest K.C. <everestkc@...restkc.com.np>
> > ---
> >   drivers/pinctrl/pinctrl-th1520.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pinctrl/pinctrl-th1520.c b/drivers/pinctrl/pinctrl-th1520.c
> > index 7474d8da32f9..07f8b51fb294 100644
> > --- a/drivers/pinctrl/pinctrl-th1520.c
> > +++ b/drivers/pinctrl/pinctrl-th1520.c
> > @@ -803,11 +803,13 @@ static int th1520_pinmux_set_mux(struct pinctrl_dev *pctldev,
> >   {
> >       struct th1520_pinctrl *thp = pinctrl_dev_get_drvdata(pctldev);
> >       const struct function_desc *func = pinmux_generic_get_function(pctldev, fsel);
> > -     enum th1520_muxtype muxtype = (uintptr_t)func->data;
> > +     enum th1520_muxtype muxtype;
> >
> >       if (!func)
> >               return -EINVAL;
> >
> > +     muxtype = (uintptr_t)func->data;
> > +
> >       return th1520_pinmux_set(thp, thp->desc.pins[gsel].number,
> >                                th1520_pad_muxdata(thp->desc.pins[gsel].drv_data),
> >                                muxtype);
>
> Otherwise looks good to me. With the change to short log:
>
> Reviewed-by: Shuah Khan <skhan@...uxfoundation.org>
The patch sent by another patch submitter has already been
applied for this issue.
https://lore.kernel.org/all/20241016155655.334518-1-colin.i.king@gmail.com/
> thanks,
> -- Shuah
>
Thanks,
Everest K.C.