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ec952aa253
The mtd driver has similar problems than the one that was fixed in
commit dc3216b141 ("super: ensure valid info").
The kill_mtd_super() helper calls shuts the superblock down but leaves
the superblock on fs_supers as the devices are still in use but puts the
mtd device and cleans out the superblock's s_mtd field.
This means another mounter can find the superblock on the list accessing
its s_mtd field while it is curently in the process of being freed or
already freed.
Prevent that from happening by keying superblock by dev_t just as we do
in the generic code.
Link: https://lore.kernel.org/linux-fsdevel/20230829-weitab-lauwarm-49c40fc85863@brauner
Acked-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Message-Id: <20230829-vfs-super-mtd-v1-2-fecb572e5df3@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>