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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, Oleksandr Ocheretnyi <oocheret@cisco.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.17 098/225] mtd: fix part field data corruption in mtd_info
Date:   Wed,  4 May 2022 18:45:36 +0200
Message-Id: <20220504153119.521567314@linuxfoundation.org>
In-Reply-To: <20220504153110.096069935@linuxfoundation.org>
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From: Oleksandr Ocheretnyi <oocheret@cisco.com>

[ Upstream commit 37c5f9e80e015d0df17d0c377c18523002986851 ]

Commit 46b5889cc2c5 ("mtd: implement proper partition handling")
started using "mtd_get_master_ofs()" in mtd callbacks to determine
memory offsets by means of 'part' field from mtd_info, what previously
was smashed accessing 'master' field in the mtd_set_dev_defaults() method.
That provides wrong offset what causes hardware access errors.

Just make 'part', 'master' as separate fields, rather than using
union type to avoid 'part' data corruption when mtd_set_dev_defaults()
is called.

Fixes: 46b5889cc2c5 ("mtd: implement proper partition handling")
Signed-off-by: Oleksandr Ocheretnyi <oocheret@cisco.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220417184649.449289-1-oocheret@cisco.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/mtd/mtd.h | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 1ffa933121f6..12ed7bb071be 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -392,10 +392,8 @@ struct mtd_info {
 	/* List of partitions attached to this MTD device */
 	struct list_head partitions;
 
-	union {
-		struct mtd_part part;
-		struct mtd_master master;
-	};
+	struct mtd_part part;
+	struct mtd_master master;
 };
 
 static inline struct mtd_info *mtd_get_master(struct mtd_info *mtd)
-- 
2.35.1