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Commit bd691922 authored by NeilBrown's avatar NeilBrown
Browse files

md: clear mddev->private when it has been freed. 



If ->private is set when ->run is called, it is assumed to be
a 'config'  prepared as part of 'reshape'.

So it is important when we free that config, that we also clear ->private.
This is not often a problem as the mddev will normally be discarded
shortly after the config us freed.
However if an 'assemble' races with a final close, the assemble can use
the old mddev which has a stale ->private.  This leads to any of
various sorts of crashes.

So clear ->private after calling ->free().

Reported-by: default avatarNate Clark <nate@neworld.us>
Cc: stable@vger.kernel.org (v4.0+)
Fixes: afa0f557 ("md: rename ->stop to ->free")
Signed-off-by: default avatarNeilBrown <neilb@suse.com>
parent 4e023612

drivers/md/md.c

+3 −0
Original line number Diff line number Diff line
@@ -5178,6 +5178,7 @@ int md_run(struct mddev *mddev) 
		mddev_detach(mddev);

		if (mddev->private)

			pers->free(mddev, mddev->private);

		mddev->private = NULL;

		module_put(pers->owner);

		bitmap_destroy(mddev);

		return err;
@@ -5313,6 +5314,7 @@ static void md_clean(struct mddev *mddev) 
	mddev->changed = 0;

	mddev->degraded = 0;

	mddev->safemode = 0;

	mddev->private = NULL;

	mddev->merge_check_needed = 0;

	mddev->bitmap_info.offset = 0;

	mddev->bitmap_info.default_offset = 0;
@@ -5385,6 +5387,7 @@ static void __md_stop(struct mddev *mddev) 
	mddev->pers = NULL;

	spin_unlock(&mddev->lock);

	pers->free(mddev, mddev->private);

	mddev->private = NULL;

	if (pers->sync_request && mddev->to_remove == NULL)

		mddev->to_remove = &md_redundancy_group;

	module_put(pers->owner);