linux-kernel - [PATCH 3.14 077/130] dm btree: fix bufio buffer leaks in dm_btree

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Message-Id: <20160301234502.529872311@linuxfoundation.org>
Date:	Tue, 01 Mar 2016 23:51:16 +0000
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	<linux-kernel@...r.kernel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<stable@...r.kernel.org>, Joe Thornber <ejt@...hat.com>,
	Mike Snitzer <snitzer@...hat.com>
Subject: [PATCH 3.14 077/130] dm btree: fix bufio buffer leaks in dm_btree_del() error path

3.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Joe Thornber <ejt@...hat.com>

commit ed8b45a3679eb49069b094c0711b30833f27c734 upstream.

If dm_btree_del()'s call to push_frame() fails, e.g. due to
btree_node_validator finding invalid metadata, the dm_btree_del() error
path must unlock all frames (which have active dm-bufio buffers) that
were pushed onto the del_stack.

Otherwise, dm_bufio_client_destroy() will BUG_ON() because dm-bufio
buffers have leaked, e.g.:
  device-mapper: bufio: leaked buffer 3, hold count 1, list 0

Signed-off-by: Joe Thornber <ejt@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/persistent-data/dm-btree.c |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -250,6 +250,16 @@ static void pop_frame(struct del_stack *
 	dm_tm_unlock(s->tm, f->b);
 }
 
+static void unlock_all_frames(struct del_stack *s)
+{
+	struct frame *f;
+
+	while (unprocessed_frames(s)) {
+		f = s->spine + s->top--;
+		dm_tm_unlock(s->tm, f->b);
+	}
+}
+
 int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
 {
 	int r;
@@ -306,9 +316,13 @@ int dm_btree_del(struct dm_btree_info *i
 			pop_frame(s);
 		}
 	}
-
 out:
+	if (r) {
+		/* cleanup all frames of del_stack */
+		unlock_all_frames(s);
+	}
 	kfree(s);
+
 	return r;
 }
 EXPORT_SYMBOL_GPL(dm_btree_del);