linux-kernel - [PATCH AUTOSEL for 4.9 175/281] mtd: nand: check ecc->total sanity in nand_scan

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Date:   Mon, 19 Mar 2018 16:01:20 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 175/281] mtd: nand: check ecc->total sanity in
 nand_scan_tail

From: Masahiro Yamada <yamada.masahiro@...ionext.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@...ionext.com>
Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/mtd/nand/nand_base.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 21c03086bb7f..3bfa8e0e44cf 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -4780,6 +4780,11 @@ 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
-- 
2.14.1