[PATCH] ocfs2: Fix a use after free on error

From: Dan Carpenter <dan.carpenter@oracle.com>
To: Mark Fasheh <mark@fasheh.com>, Jiri Slaby <jirislaby@kernel.org>
Cc: Joel Becker <jlbec@evilplan.org>,
	Joseph Qi <joseph.qi@linux.alibaba.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alex Shi <alex.shi@linux.alibaba.com>,
	Jens Axboe <axboe@kernel.dk>,
	ocfs2-devel@oss.oracle.com, linux-kernel@vger.kernel.org,
	kernel-janitors@vger.kernel.org
Subject: [PATCH] ocfs2: Fix a use after free on error
Date: Mon, 1 Feb 2021 15:25:43 +0300	[thread overview]
Message-ID: <YBfzR7AbZZ4Pp6sq@mwanda> (raw)

The error handling in this function frees "reg" but it is still on the
"o2hb_all_regions" list so it will lead to a use after free.  The fix
for this is to only add it to the list after everything has succeeded.

Fixes: 1cf257f51191 ("ocfs2: fix memory leak")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
This is from static analysis and hasn't been tested.

 fs/ocfs2/cluster/heartbeat.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 0179a73a3fa2..92af4dc813e7 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -2025,7 +2025,6 @@ static struct config_item *o2hb_heartbeat_group_make_item(struct config_group *g
 		}
 		set_bit(reg->hr_region_num, o2hb_region_bitmap);
 	}
-	list_add_tail(&reg->hr_all_item, &o2hb_all_regions);
 	spin_unlock(&o2hb_live_lock);
 
 	config_item_init_type_name(&reg->hr_item, name, &o2hb_region_type);
@@ -2053,6 +2052,10 @@ static struct config_item *o2hb_heartbeat_group_make_item(struct config_group *g
 
 	o2hb_debug_region_init(reg, o2hb_debug_dir);
 
+	spin_lock(&o2hb_live_lock);
+	list_add_tail(&reg->hr_all_item, &o2hb_all_regions);
+	spin_unlock(&o2hb_live_lock);
+
 	return &reg->hr_item;
 
 unregister_handler:
-- 
2.29.2

