linux-kernel - Re: [PATCH] [REGRESSION] i2c-acpi: Fix NULL Pointer dereference

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Message-ID: <1696265.yGhHYgE97A@vostro.rjw.lan>
Date:	Wed, 24 Sep 2014 23:06:24 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Peter Huewe <peterhuewe@....de>, Wolfram Sang <wsa@...-dreams.de>
Cc:	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	linux-i2c@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [REGRESSION] i2c-acpi: Fix NULL Pointer dereference

Hi Wolfram,

Do you want me to take care of this or are you going to handle it?

It has been ACKed by Mika already: https://patchwork.kernel.org/patch/4897751/

Rafael


On Friday, September 12, 2014 09:09:47 PM Peter Huewe wrote:
> If adapter->dev.parent == NULL there is a NULL pointer dereference in
> acpi_i2c_install_space_handler and acpi_i2c_remove_space_handler.
> 
> This is present since introduction of this code:
> 366047515c6e "i2c: rework kernel config I2C_ACPI" or even
> da3c6647ee08 "I2C/ACPI: Clean up I2C ACPI code and Add CONFIG_I2C_ACPI"
> 
> The adapter->dev.parent == NULL case is valid for the i2c_stub,
> so loading i2c_stub with ACPI_I2C_OPREGION enabled results in an oops.
> This is also valid at least for i2c_tiny_usb and i2c_robotfuzz_osif.
> 
> Fix by checking whether it is null before calling ACPI_HANDLE.
> 
> Signed-off-by: Peter Huewe <peterhuewe@....de>
> ---
>  drivers/i2c/i2c-acpi.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-acpi.c b/drivers/i2c/i2c-acpi.c
> index 0dbc18c..c456b17 100644
> --- a/drivers/i2c/i2c-acpi.c
> +++ b/drivers/i2c/i2c-acpi.c
> @@ -308,10 +308,15 @@ acpi_i2c_space_handler(u32 function, acpi_physical_address command,
>  
>  int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
>  {
> -	acpi_handle handle = ACPI_HANDLE(adapter->dev.parent);
> +	acpi_handle handle;
>  	struct acpi_i2c_handler_data *data;
>  	acpi_status status;
>  
> +	if (!adapter->dev.parent)
> +		return -ENODEV;
> +
> +	handle = ACPI_HANDLE(adapter->dev.parent);
> +
>  	if (!handle)
>  		return -ENODEV;
>  
> @@ -344,10 +349,15 @@ int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
>  
>  void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter)
>  {
> -	acpi_handle handle = ACPI_HANDLE(adapter->dev.parent);
> +	acpi_handle handle;
>  	struct acpi_i2c_handler_data *data;
>  	acpi_status status;
>  
> +	if (!adapter->dev.parent)
> +		return;
> +
> +	handle = ACPI_HANDLE(adapter->dev.parent);
> +
>  	if (!handle)
>  		return;
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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