linux-kernel - [PATCH v2] nvmem: u-boot-env: fix crc32_data

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Message-Id: <70a16eae113e08db2390b76e174f4837caa135c3.1667580636.git.chunkeey@gmail.com>
Date:   Fri,  4 Nov 2022 17:52:03 +0100
From:   Christian Lamparter <chunkeey@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     rafal@...ecki.pl, srinivas.kandagatla@...aro.org,
        gregkh@...uxfoundation.org, a.fatoum@...gutronix.de
Subject: [PATCH v2] nvmem: u-boot-env: fix crc32_data_offset on redundant u-boot-env

The Western Digital MyBook Live (PowerPC 464/APM82181)
has a set of redundant u-boot-env. Loading up the driver
the following error:

| u_boot_env: Invalid calculated CRC32: 0x4f8f2c86 (expected: 0x98b14514)
| u_boot_env: probe of partition@...00 failed with error -22

Looking up the userspace libubootenv utilities source [0],
it looks like the "mark" or "flag" is not part of the
crc32 sum... which is unfortunate :(

|static int libuboot_load(struct uboot_ctx *ctx)
|{
|[...]
|       if (ctx->redundant) {
|		[...]
|               offsetdata = offsetof(struct uboot_env_redund, data);
|		[...]					//-----^^
|       }
|       usable_envsize = ctx->size - offsetdata;
|       buf[0] = malloc(bufsize);
|[...]
|	for (i = 0; i < copies; i++) {
|		data = (uint8_t *)(buf[i] + offsetdata);
|               uint32_t crc;
|
|		ret = devread(ctx, i, buf[i]);
|		[...]
|		crc = *(uint32_t *)(buf[i] + offsetcrc);
|               dev->crc = crc32(0, (uint8_t *)data, usable_envsize);
|

[0] https://github.com/sbabic/libubootenv/blob/master/src/uboot_env.c#L951
Fixes: d5542923f200 ("nvmem: add driver handling U-Boot environment variables")
Signed-off-by: Christian Lamparter <chunkeey@...il.com>
---
v1->v2:
	- drop endian crc32 check - handled by pending patch
	- added u-boot-env: tag to subject + adjusted subject
---
 drivers/nvmem/u-boot-env.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c
index 8e72d1bbd649..4fdbdccebda1 100644
--- a/drivers/nvmem/u-boot-env.c
+++ b/drivers/nvmem/u-boot-env.c
@@ -135,7 +135,7 @@ static int u_boot_env_parse(struct u_boot_env *priv)
 		break;
 	case U_BOOT_FORMAT_REDUNDANT:
 		crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32);
-		crc32_data_offset = offsetof(struct u_boot_env_image_redundant, mark);
+		crc32_data_offset = offsetof(struct u_boot_env_image_redundant, data);
 		data_offset = offsetof(struct u_boot_env_image_redundant, data);
 		break;
 	}
-- 
2.38.1