From b5094b7f135be34630e3ea8a98fa215715d0f29d Mon Sep 17 00:00:00 2001
From: Richard Weinberger <richard@nod.at>
Date: Sat, 3 Mar 2018 11:45:54 +0100
Subject: [PATCH] ubi: Reject MLC NAND
Git-commit: b5094b7f135be34630e3ea8a98fa215715d0f29d
Patch-mainline: v4.17-rc1
References: bsc#1051510

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

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

--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -843,6 +843,17 @@ 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++)