linux-kernel - Re: [PATCH][next] pinctrl: th1520: Fix potential null pointer dereference on func

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Message-ID: <ZxACrl/0hUE62eGN@x1>
Date: Wed, 16 Oct 2024 11:15:10 -0700
From: Drew Fustini <dfustini@...storrent.com>
To: Colin Ian King <colin.i.king@...il.com>
Cc: Drew Fustini <drew@...7.com>, Guo Ren <guoren@...nel.org>,
	Fu Wei <wefu@...hat.com>, Linus Walleij <linus.walleij@...aro.org>,
	Emil Renner Berthing <emil.renner.berthing@...onical.com>,
	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: Fix potential null pointer
 dereference on func

On Wed, Oct 16, 2024 at 04:56:55PM +0100, Colin Ian King wrote:
> The initialization of muxtype deferences pointer func before func
> is sanity checked with a null pointer check, hence we have a null
> pointer deference issue. Fix this by only deferencing func with
> the assignment to muxtype after func has been null pointer checked.
> 
> Fixes: 1fc30cd92770 ("pinctrl: th1520: Factor out casts")
> Signed-off-by: Colin Ian King <colin.i.king@...il.com>
> ---
>  drivers/pinctrl/pinctrl-th1520.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pinctrl/pinctrl-th1520.c b/drivers/pinctrl/pinctrl-th1520.c
> index 7474d8da32f9..e641bad6728c 100644
> --- a/drivers/pinctrl/pinctrl-th1520.c
> +++ b/drivers/pinctrl/pinctrl-th1520.c
> @@ -803,11 +803,12 @@ 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);
> -- 
> 2.39.5
> 

Acked-by: Drew Fustini <dfustini@...storrent.com>

I've tested this on top of next-20241016 on the BeagleV Ahead and
LicheePi 4A.

thanks,
drew