[PATCH 4.9 170/310] mtd: nand: check ecc->total sanity in nand_scan_tail

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>


[ 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@xxxxxxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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