linux-kernel - Re: [PATCH] platform/x86: panasonic-laptop: fix NULL dereference

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Date: Fri, 29 Mar 2024 01:21:27 +0100
From: Armin Wolf <W_Armin@....de>
To: Maxim Korotkov <korotkov.maxim.s@...il.com>,
 Kenneth Chan <kenneth.t.chan@...il.com>
Cc: Len Brown <len.brown@...el.com>,
 Henrique de Moraes Holschuh <hmh@....eng.br>,
 Harald Welte <laforge@...monks.org>, Matthew Garrett <mjg@...hat.com>,
 Ivan Kapranov <i.kapranov@...uritycode.ru>, lvc-project@...uxtesting.org,
 platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] platform/x86: panasonic-laptop: fix NULL dereference

Am 28.03.24 um 11:35 schrieb Maxim Korotkov:

> When initializing the pcc by calling acpi_driver_data(), the "device"
> pointer was dereferenced without checking for NULL. This seems like
> a logical mistake.
>
> Added a pointer check to ensure that it is valid
> before using it for pcc initialization.

Hi,

is this check even needed? I think the ACPI driver core takes care
of passing a valid ACPI device pointer to acpi_pcc_hotkey_remove().

Thanks,
Armin Wolf

> Found by Security Code and Linux Verification Center(linuxtesting.org)
>
> Fixes: 709ee531c153 ("panasonic-laptop: add Panasonic Let's Note laptop extras driver v0.94")
>
> Signed-off-by: Maxim Korotkov <korotkov.maxim.s@...il.com>
> ---
>   drivers/platform/x86/panasonic-laptop.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
> index cf845ee1c7b1..de29758b0384 100644
> --- a/drivers/platform/x86/panasonic-laptop.c
> +++ b/drivers/platform/x86/panasonic-laptop.c
> @@ -1067,9 +1067,12 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
>
>   static void acpi_pcc_hotkey_remove(struct acpi_device *device)
>   {
> -	struct pcc_acpi *pcc = acpi_driver_data(device);
> +	struct pcc_acpi *pcc;
>
> -	if (!device || !pcc)
> +	if (!device)
> +		return;
> +	pcc = acpi_driver_data(device);
> +	if (!pcc)
>   		return;
>
>   	i8042_remove_filter(panasonic_i8042_filter);