From: NeilBrown <neilb@suse.de>
Date: Thu, 25 Jun 2015 07:01:40 +0000 (+1000)
Subject: md: clear mddev->private when it has been freed.
X-Git-Tag: v4.1.4~82
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=adeb846a6d8fdc8b9dc19a65393382838cad727f;p=users%2Fjedix%2Flinux-maple.git

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

commit bd6919228d7e1867ae9e24ab27e3e4a366c87d21 upstream.

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: Nate Clark <nate@neworld.us>
Fixes: afa0f557cb15 ("md: rename ->stop to ->free")
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4dbed4a67aaf4..5b7c914908cdc 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5159,6 +5159,7 @@ 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;
@@ -5294,6 +5295,7 @@ 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;
@@ -5366,6 +5368,7 @@ 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);