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

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Message-ID: <20250623070901.1733755-1-steffen@innosonix.de>
Date: Mon, 23 Jun 2025 09:08:49 +0200
From: Steffen Bätz <steffen@...osonix.de>
To: 
Cc: Steffen Bätz <steffen@...osonix.de>,
	Srinivas Kandagatla <srini@...nel.org>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Dmitry Baryshkov <lumag@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] nvmem: imx-ocotp: fix MAC address byte length

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@...osonix.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


-- 


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