linux-kernel - [PATCH 3.16 084/370] dm space map metadata: fix 'struct sm

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Message-ID: <lsq.1489146382.685611257@decadent.org.uk>
Date:   Fri, 10 Mar 2017 11:46:22 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Benjamin Marzinski" <bmarzins@...hat.com>,
        "Mike Snitzer" <snitzer@...hat.com>,
        "Joe Thornber" <ejt@...hat.com>
Subject: [PATCH 3.16 084/370] dm space map metadata: fix 'struct
 sm_metadata' leak on failed create

3.16.42-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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'.

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: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/md/persistent-data/dm-space-map-metadata.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

--- a/drivers/md/persistent-data/dm-space-map-metadata.c
+++ b/drivers/md/persistent-data/dm-space-map-metadata.c
@@ -773,17 +773,15 @@ int dm_sm_metadata_create(struct dm_spac
 	memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
 
 	r = sm_ll_new_metadata(&smm->ll, tm);
+	if (!r) {
+		if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
+			nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
+		r = sm_ll_extend(&smm->ll, nr_blocks);
+	}
+	memcpy(&smm->sm, &ops, sizeof(smm->sm));
 	if (r)
 		return r;
 
-	if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
-		nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
-	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.