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

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Date: Thu, 28 Mar 2024 14:53:46 -0700
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
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


On 3/28/24 3:35 AM, Maxim Korotkov wrote:
> 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.
>
> Found by Security Code and Linux Verification Center(linuxtesting.org)
>
> Fixes: 709ee531c153 ("panasonic-laptop: add Panasonic Let's Note laptop extras driver v0.94")

Since this is a remove function within kernel, is there any change for
device being NULL?

> 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);

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer