From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ipmail04.adl6.internode.on.net ([150.101.137.141]) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1OHSAO-0000Jc-VK for linux-mtd@lists.infradead.org; Thu, 27 May 2010 01:45:49 +0000 Message-ID: <4BFDCEC3.7070601@elphinstone.net> Date: Thu, 27 May 2010 11:45:39 +1000 From: Mark Ware MIME-Version: 1.0 To: linux-mtd@lists.infradead.org Subject: [RFC/PATCH] doc2000: Fix uninitialized variable in doc_ecc_decode() Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Thomas Gleixner List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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