[PATCH 5.10 060/129] mtd: fix part field data corruption in mtd_info

Greg Kroah-Hartman
2022-05-04T17:08:52Z

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 157357ec1441..fc41fecfe44f 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -388,10 +388,8 @@ 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