[PATCH v3] nvmem: imx-ocotp: fix MAC address byte length
Alexander Stein
alexander.stein at ew.tq-group.com
Thu Jul 3 06:41:40 PDT 2025
Am Montag, 23. Juni 2025, 19:09:55 CEST schrieb Steffen Bätz:
> 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")
> Cc: stable at vger.kernel.org
> Signed-off-by: Steffen Bätz <steffen at innosonix.de>
Tested-by: Alexander Stein <alexander.stein at ew.tq-group.com>
Thanks
> ---
> v3:
> - replace magic number 6 with ETH_ALEN
> - Fix misleading indentation and properly group 'mac-address' statements
> v2:
> - Add Cc: stable at vger.kernel.org as requested by Greg KH's patch bot
> drivers/nvmem/imx-ocotp-ele.c | 6 +++++-
> drivers/nvmem/imx-ocotp.c | 6 +++++-
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvmem/imx-ocotp-ele.c b/drivers/nvmem/imx-ocotp-ele.c
> index ca6dd71d8a2e..9ef01c91dfa6 100644
> --- a/drivers/nvmem/imx-ocotp-ele.c
> +++ b/drivers/nvmem/imx-ocotp-ele.c
> @@ -12,6 +12,7 @@
> #include <linux/of.h>
> #include <linux/platform_device.h>
> #include <linux/slab.h>
> +#include <linux/if_ether.h> /* ETH_ALEN */
>
> enum fuse_type {
> FUSE_FSB = BIT(0),
> @@ -118,9 +119,12 @@ static int imx_ocotp_cell_pp(void *context, const char *id, int index,
> int i;
>
> /* Deal with some post processing of nvmem cell data */
> - if (id && !strcmp(id, "mac-address"))
> + if (id && !strcmp(id, "mac-address")) {
> + if (bytes > ETH_ALEN)
> + bytes = ETH_ALEN;
> for (i = 0; i < bytes / 2; i++)
> swap(buf[i], buf[bytes - i - 1]);
> + }
>
> return 0;
> }
> diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c
> index 79dd4fda0329..1343cafc37cc 100644
> --- a/drivers/nvmem/imx-ocotp.c
> +++ b/drivers/nvmem/imx-ocotp.c
> @@ -23,6 +23,7 @@
> #include <linux/platform_device.h>
> #include <linux/slab.h>
> #include <linux/delay.h>
> +#include <linux/if_ether.h> /* ETH_ALEN */
>
> #define IMX_OCOTP_OFFSET_B0W0 0x400 /* Offset from base address of the
> * OTP Bank0 Word0
> @@ -227,9 +228,12 @@ static int imx_ocotp_cell_pp(void *context, const char *id, int index,
> int i;
>
> /* Deal with some post processing of nvmem cell data */
> - if (id && !strcmp(id, "mac-address"))
> + if (id && !strcmp(id, "mac-address")) {
> + if (bytes > ETH_ALEN)
> + bytes = ETH_ALEN;
> for (i = 0; i < bytes / 2; i++)
> swap(buf[i], buf[bytes - i - 1]);
> + }
>
> return 0;
> }
>
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