Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Richard Weinberger <richard@nod.at>
To:     linux-mtd@lists.infradead.org
Cc:     linux-kernel@vger.kernel.org, cyrille.pitchen@wedev4u.fr,
        marek.vasut@gmail.com, boris.brezillon@free-electrons.com,
        computersforpeace@gmail.com, dwmw2@infradead.org, richard@nod.at,
        dedekind1@gmail.com, tharvey@gateworks.com, stable@vger.kernel.org
Subject: [PATCH] ubi: Reject MLC NAND
Date:   Sat,  3 Mar 2018 11:45:54 +0100
Message-Id: <20180303104554.5958-1-richard@nod.at>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index e941395de3ae..753494e042d5 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -854,6 +854,17 @@ 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++)
-- 
2.13.6