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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, Richard Weinberger <richard@nod.at>,
        Boris Brezillon <boris.brezillon@bootlin.com>,
        Artem Bityutskiy <dedekind1@gmail.com>
Subject: [PATCH 4.4 25/97] ubi: Reject MLC NAND
Date:   Sun, 22 Apr 2018 15:53:03 +0200
Message-Id: <20180422135306.451761209@linuxfoundation.org>
In-Reply-To: <20180422135304.577223025@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Richard Weinberger <richard@nod.at>

commit b5094b7f135be34630e3ea8a98fa215715d0f29d upstream.

While UBI and UBIFS seem to work at first sight with MLC NAND, you will
most likely lose all your data upon a power-cut or due to read/write
disturb.
In order to protect users from bad surprises, refuse to attach to MLC
NAND.

Cc: stable@vger.kernel.org
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Boris Brezillon <boris.brezillon@bootlin.com>
Acked-by: Artem Bityutskiy <dedekind1@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/mtd/ubi/build.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -889,6 +889,17 @@ int ubi_attach_mtd_dev(struct mtd_info *
 		return -EINVAL;
 	}
 
+	/*
+	 * Both UBI and UBIFS have been designed for SLC NAND and NOR flashes.
+	 * MLC NAND is different and needs special care, otherwise UBI or UBIFS
+	 * will die soon and you will lose all your data.
+	 */
+	if (mtd->type == MTD_MLCNANDFLASH) {
+		pr_err("ubi: refuse attaching mtd%d - MLC NAND is not supported\n",
+			mtd->index);
+		return -EINVAL;
+	}
+
 	if (ubi_num == UBI_DEV_NUM_AUTO) {
 		/* Search for an empty slot in the @ubi_devices array */
 		for (ubi_num = 0; ubi_num < UBI_MAX_DEVICES; ubi_num++)