linux-kernel - Re: [PATCH] drivers:of: Add null check for bus in of_match

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Message-ID: <CAL_Jsq+UQ+Epe=_UyR-nkTWsbT6Q9HeEqX6__9nb+Uv1vzZCmA@mail.gmail.com>
Date: Thu, 13 Jun 2024 09:44:52 -0600
From: Rob Herring <robh@...nel.org>
To: Gyeonggeon Choi <gychoi.dev@...il.com>
Cc: saravanak@...gle.com, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers:of: Add null check for bus in of_match_bus

On Thu, Jun 13, 2024 at 9:02 AM Gyeonggeon Choi <gychoi.dev@...il.com> wrote:
>
> Added a null check for the bus variable after calling of_match_bus.
> This prevents potential null pointer dereference errors in subsequent
> code, where bus->count_cells could cause a crash if bus is NULL.

Go read of_match_bus(). It never returns NULL and if somehow it did,
we'll BUG() first.

>
> Signed-off-by: Gyeonggeon Choi <gychoi.dev@...il.com>
> ---
>  drivers/of/address.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index d669ce25b5f9..85f986d25870 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -504,6 +504,8 @@ static u64 __of_translate_address(struct device_node *node,
>         if (parent == NULL)
>                 return OF_BAD_ADDR;
>         bus = of_match_bus(parent);
> +       if (bus == NULL)
> +               return OF_BAD_ADDR;
>
>         /* Count address cells & copy address locally */
>         bus->count_cells(dev, &na, &ns);
> --
> 2.39.3 (Apple Git-146)
>