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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Boris Brezillon <boris.brezillon@free-electrons.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 170/310] mtd: nand: check ecc->total sanity in nand_scan_tail
Date:   Wed, 11 Apr 2018 20:35:09 +0200
Message-Id: <20180411183629.954638344@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Masahiro Yamada <yamada.masahiro@socionext.com>


[ Upstream commit 79e0348c4e24fd1affdcf055e0269755580e0fcc ]

Drivers are supposed to set correct ecc->{size,strength,bytes} before
calling nand_scan_tail(), but it does not complain about ecc->total
bigger than oobsize.

In this case, chip->scan_bbt() crashes due to memory corruption, but
it is hard to debug.  It would be kind to fail it earlier with a clear
message.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/mtd/nand/nand_base.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -4785,6 +4785,11 @@ int nand_scan_tail(struct mtd_info *mtd)
 		goto err_free;
 	}
 	ecc->total = ecc->steps * ecc->bytes;
+	if (ecc->total > mtd->oobsize) {
+		WARN(1, "Total number of ECC bytes exceeded oobsize\n");
+		ret = -EINVAL;
+		goto err_free;
+	}
 
 	/*
 	 * The number of bytes available for a client to place data into