Re: [PATCH] nvmem: imx-ocotp: fix MAC address byte length

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Jun 23, 2025 at 09:08:49AM +0200, Steffen Bätz wrote:
> The commit "13bcd440f2ff nvmem: core: verify cell's raw_len" caused an
> extension of the "mac-address" cell from 6 to 8 bytes due to word_size
> of 4 bytes.
> 
> Thus, the required byte swap for the mac-address of the full buffer length,
> caused an trucation of the read mac-address.
> >From the original address 70:B3:D5:14:E9:0E to 00:00:70:B3:D5:14
> 
> After swapping only the first 6 bytes, the mac-address is correctly passed
> to the upper layers.
> 
> Fixes: 13bcd440f2ff ("nvmem: core: verify cell's raw_len")
> Signed-off-by: Steffen Bätz <steffen@innosonix.de>
> ---
>  drivers/nvmem/imx-ocotp-ele.c | 2 ++
>  drivers/nvmem/imx-ocotp.c     | 2 ++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/nvmem/imx-ocotp-ele.c b/drivers/nvmem/imx-ocotp-ele.c
> index ca6dd71d8a2e..3af7968f5a34 100644
> --- a/drivers/nvmem/imx-ocotp-ele.c
> +++ b/drivers/nvmem/imx-ocotp-ele.c
> @@ -119,6 +119,8 @@ static int imx_ocotp_cell_pp(void *context, const char *id, int index,
>  
>  	/* Deal with some post processing of nvmem cell data */
>  	if (id && !strcmp(id, "mac-address"))
> +		if (bytes > 6)
> +			bytes = 6;
>  		for (i = 0; i < bytes / 2; i++)
>  			swap(buf[i], buf[bytes - i - 1]);
>  
> diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c
> index 79dd4fda0329..63e9974d9618 100644
> --- a/drivers/nvmem/imx-ocotp.c
> +++ b/drivers/nvmem/imx-ocotp.c
> @@ -228,6 +228,8 @@ static int imx_ocotp_cell_pp(void *context, const char *id, int index,
>  
>  	/* Deal with some post processing of nvmem cell data */
>  	if (id && !strcmp(id, "mac-address"))
> +		if (bytes > 6)
> +			bytes = 6;
>  		for (i = 0; i < bytes / 2; i++)
>  			swap(buf[i], buf[bytes - i - 1]);
>  
> -- 
> 2.43.0
> 
> 
> -- 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
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