From: Richard Weinberger <richard@nod.at>
Date: Sat, 3 Mar 2018 10:45:54 +0000 (+0100)
Subject: ubi: Reject MLC NAND
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=577b4eb23811dfc8e38924dc476dbc866be74253;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

ubi: Reject MLC NAND

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>
---

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 842550b5712a..defb1cd8d2e1 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -845,6 +845,17 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 		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++)