openwrt/target/linux/brcm63xx/patches-3.7/005-MIPS-BCM63XX-fix-nvram-checksum-calculation.patch

From 7180de9a27ce433efc15bc1982b9a9e4ba3c48dc Mon Sep 17 00:00:00 2001
From: Jonas Gorski <jonas.gorski@gmail.com>
Date: Sat, 10 Nov 2012 02:04:58 +0100
Subject: [PATCH] MIPS: BCM63XX: fix nvram checksum calculation

The current checksum calculation code does nothing except checking that
the first byte of nvram is 0 without actually checking the checksum.

Implement the correct checksum calculation by calculating the crc32 with
the checksum field set to 0.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
---

This patch depends on the previous nvram patch ("move nvram functions
into their own file").

 arch/mips/bcm63xx/nvram.c |   23 +++++++++++++----------
 1 files changed, 13 insertions(+), 10 deletions(-)

--- a/arch/mips/bcm63xx/nvram.c
+++ b/arch/mips/bcm63xx/nvram.c
@@ -11,6 +11,7 @@
 #define pr_fmt(fmt) "bcm63xx_nvram: " fmt
 
 #include <linux/init.h>
+#include <linux/crc32.h>
 #include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/if_ether.h>
@@ -40,23 +41,25 @@ static int mac_addr_used;
 int __init bcm63xx_nvram_init(void *addr)
 {
 	unsigned int check_len;
-	u8 *p;
-	u32 val;
+	u32 crc, expected_crc;
 
 	/* extract nvram data */
 	memcpy(&nvram, addr, sizeof(nvram));
 
 	/* check checksum before using data */
-	if (nvram.version <= 4)
-		check_len = offsetof(struct bcm963xx_nvram, checksum_old);
-	else
+	if (nvram.version <= 4) {
+		check_len = offsetof(struct bcm963xx_nvram, reserved3);
+		expected_crc = nvram.checksum_old;
+		nvram.checksum_old = 0;
+	} else {
 		check_len = sizeof(nvram);
-	val = 0;
-	p = (u8 *)&nvram;
+		expected_crc = nvram.checksum_high;
+		nvram.checksum_high = 0;
+	}
 
-	while (check_len--)
-		val += *p;
-	if (val)
+	crc = crc32_le(~0, (u8 *)&nvram, check_len);
+
+	if (crc != expected_crc)
 		return -EINVAL;
 
 	return 0;