Subject: Re: [PATCH v2] i2c: cpm: Fix i2c_ram structure

From: Wolfram Sang <[email-masked]>
Date: Wed, 23 Sep 2020 18:08:29 +0200

On Wed, Sep 23, 2020 at 04:08:40PM +0200, [email-masked] wrote:
> From: Nicolas VINCENT <[email-masked]>
> 
> the i2c_ram structure is missing the sdmatmp field mentionned in
> datasheet for MPC8272 at paragraph 36.5. With this field missing, the
> hardware would write past the allocated memory done through
> cpm_muram_alloc for the i2c_ram structure and land in memory allocated
> for the buffers descriptors corrupting the cbd_bufaddr field. Since this
> field is only set during setup(), the first i2c transaction would work
> and the following would send data read from an arbitrary memory
> location.
> 
> Signed-off-by: Nicolas VINCENT <[email-masked]>

Thanks!

Is someone able to identify a Fixes: tag I could add?

> ---
>  drivers/i2c/busses/i2c-cpm.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c
> index 1213e1932ccb..24d584a1c9a7 100644
> --- a/drivers/i2c/busses/i2c-cpm.c
> +++ b/drivers/i2c/busses/i2c-cpm.c
> @@ -65,6 +65,9 @@ struct i2c_ram {
>  	char    res1[4];	/* Reserved */
>  	ushort  rpbase;		/* Relocation pointer */
>  	char    res2[2];	/* Reserved */
> +	/* The following elements are only for CPM2 */
> +	char    res3[4];	/* Reserved */
> +	uint    sdmatmp;	/* Internal */
>  };
>  
>  #define I2COM_START	0x80
> -- 
> 2.17.1
>