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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, Geert Uytterhoeven <geert@linux-m68k.org>,
        Boris Brezillon <bbrezillon@kernel.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH 4.20 01/50] mtd: Make sure mtd->erasesize is valid even if the partition is of size 0
Date:   Wed, 13 Feb 2019 19:38:06 +0100
Message-Id: <20190213183655.851004077@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

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

From: Boris Brezillon <bbrezillon@kernel.org>

commit ad4635153034c20c6f6e211e2ed3fd38b658649a upstream.

Commit 33f45c44d68b ("mtd: Do not allow MTD devices with inconsistent
erase properties") introduced a check to make sure ->erasesize and
->_erase values are consistent with the MTD_NO_ERASE flag.
This patch did not take the 0 bytes partition case into account which
can happen when the defined partition is outside the flash device memory
range. Fix that by setting the partition erasesize to the parent
erasesize.

Fixes: 33f45c44d68b ("mtd: Do not allow MTD devices with inconsistent erase properties")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: <stable@vger.kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/mtd/mtdpart.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -470,6 +470,10 @@ static struct mtd_part *allocate_partiti
 		/* let's register it anyway to preserve ordering */
 		slave->offset = 0;
 		slave->mtd.size = 0;
+
+		/* Initialize ->erasesize to make add_mtd_device() happy. */
+		slave->mtd.erasesize = parent->erasesize;
+
 		printk(KERN_ERR"mtd: partition \"%s\" is out of reach -- disabled\n",
 			part->name);
 		goto out_register;