linux-kernel - [PATCH 3.10 017/268] dm space map metadata: fix 'struct sm

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Date:   Mon, 19 Jun 2017 20:28:36 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Benjamin Marzinski <bmarzins@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 017/268] dm space map metadata: fix 'struct sm_metadata' leak on failed create

From: Benjamin Marzinski <bmarzins@...hat.com>

commit 314c25c56c1ee5026cf99c570bdfe01847927acb upstream.

In dm_sm_metadata_create() we temporarily change the dm_space_map
operations from 'ops' (whose .destroy function deallocates the
sm_metadata) to 'bootstrap_ops' (whose .destroy function doesn't).

If dm_sm_metadata_create() fails in sm_ll_new_metadata() or
sm_ll_extend(), it exits back to dm_tm_create_internal(), which calls
dm_sm_destroy() with the intention of freeing the sm_metadata, but it
doesn't (because the dm_space_map operations is still set to
'bootstrap_ops').

Fix this by setting the dm_space_map operations back to 'ops' if
dm_sm_metadata_create() fails when it is set to 'bootstrap_ops'.

[js] no nr_blocks test in 3.12 yet

Signed-off-by: Benjamin Marzinski <bmarzins@...hat.com>
Acked-by: Joe Thornber <ejt@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/md/persistent-data/dm-space-map-metadata.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/md/persistent-data/dm-space-map-metadata.c b/drivers/md/persistent-data/dm-space-map-metadata.c
index 056d09c..c79d648 100644
--- a/drivers/md/persistent-data/dm-space-map-metadata.c
+++ b/drivers/md/persistent-data/dm-space-map-metadata.c
@@ -679,15 +679,13 @@ int dm_sm_metadata_create(struct dm_space_map *sm,
 	memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
 
 	r = sm_ll_new_metadata(&smm->ll, tm);
+	if (!r) {
+		r = sm_ll_extend(&smm->ll, nr_blocks);
+	}
+	memcpy(&smm->sm, &ops, sizeof(smm->sm));
 	if (r)
 		return r;
 
-	r = sm_ll_extend(&smm->ll, nr_blocks);
-	if (r)
-		return r;
-
-	memcpy(&smm->sm, &ops, sizeof(smm->sm));
-
 	/*
 	 * Now we need to update the newly created data structures with the
 	 * allocated blocks that they were built from.
-- 
2.8.0.rc2.1.gbe9624a