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

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Message-ID: <2f82fbcb-4a3c-4dfe-8852-7fc0b27c38e4@linuxfoundation.org>
Date: Wed, 16 Oct 2024 15:00:37 -0600
From: Shuah Khan <skhan@...uxfoundation.org>
To: "Everest K.C." <everestkc@...restkc.com.np>, drew@...7.com,
 guoren@...nel.org, wefu@...hat.com, linus.walleij@...aro.org
Cc: linux-riscv@...ts.infradead.org, linux-gpio@...r.kernel.org,
 kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
 Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH][next] pinctrl: th1520: Dereference pointer only after
 NULL check

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>

thanks,
-- Shuah