[RFC/PATCH] doc2000: Fix uninitialized variable in doc_ecc_decode()

[Mark Ware <mware@elphinstone.net>]

The variable 'syn' was being used uninitialized.  Also
fixed incorrect use of syn[] vs s[].

Tested on powerpc board with 64MB DOC2000.
---

I am porting from a 2.4.18 kernel to 2.6.32, and I saw random media header
mismatches causing a failure to detect the DOC device partitions.  Tracing
through, I saw this variable being used uninitialized and I suspect
incorrectly also.

I do not really understand how the ecc/syndrome code works, so I do not
know if this patch is the correct solution, but it did make my problem
go away...

CC: Thomas Gleixner as I believe he may have written this function initially.

 drivers/mtd/nand/diskonchip.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/diskonchip.c b/drivers/mtd/nand/diskonchip.c
index a5bf9ff..7da2321 100644
--- a/drivers/mtd/nand/diskonchip.c
+++ b/drivers/mtd/nand/diskonchip.c
@@ -145,6 +145,7 @@ static int doc_ecc_decode(struct rs_control *rs, uint8_t *data, uint8_t *ecc)
 	uint8_t parity;
 	uint16_t ds[4], s[5], tmp, errval[8], syn[4];
 
+	memset(syn, 0, sizeof(syn));
 	/* Convert the ecc bytes into words */
 	ds[0] = ((ecc[4] & 0xff) >> 0) | ((ecc[5] & 0x03) << 8);
 	ds[1] = ((ecc[5] & 0xfc) >> 2) | ((ecc[2] & 0x0f) << 6);
@@ -168,9 +169,9 @@ static int doc_ecc_decode(struct rs_control *rs, uint8_t *data, uint8_t *ecc)
 			s[i] ^= rs->alpha_to[rs_modnn(rs, tmp + (FCR + i) * j)];
 	}
 
-	/* Calc s[i] = s[i] / alpha^(v + i) */
+	/* Calc syn[i] = s[i] / alpha^(v + i) */
 	for (i = 0; i < NROOTS; i++) {
-		if (syn[i])
+		if (s[i])
 			syn[i] = rs_modnn(rs, rs->index_of[s[i]] + (NN - FCR - i));
 	}
 	/* Call the decoder library */
-- 
1.5.6.5