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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alexander Aring <aahringo@redhat.com>,
        David Teigland <teigland@redhat.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.9 670/757] fs: dlm: fix configfs memory leak
Date:   Tue, 27 Oct 2020 14:55:20 +0100
Message-Id: <20201027135521.971208514@linuxfoundation.org>
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From: Alexander Aring <aahringo@redhat.com>

[ Upstream commit 3d2825c8c6105b0f36f3ff72760799fa2e71420e ]

This patch fixes the following memory detected by kmemleak and umount
gfs2 filesystem which removed the last lockspace:

unreferenced object 0xffff9264f482f600 (size 192):
  comm "dlm_controld", pid 325, jiffies 4294690276 (age 48.136s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 6e 6f 64 65 73 00 00 00  ........nodes...
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000060481d7>] make_space+0x41/0x130
    [<000000008d905d46>] configfs_mkdir+0x1a2/0x5f0
    [<00000000729502cf>] vfs_mkdir+0x155/0x210
    [<000000000369bcf1>] do_mkdirat+0x6d/0x110
    [<00000000cc478a33>] do_syscall_64+0x33/0x40
    [<00000000ce9ccf01>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

The patch just remembers the "nodes" entry pointer in space as I think
it's created as subdirectory when parent "spaces" is created. In
function drop_space() we will lost the pointer reference to nds because
configfs_remove_default_groups(). However as this subdirectory is always
available when "spaces" exists it will just be freed when "spaces" will be
freed.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/dlm/config.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/dlm/config.c b/fs/dlm/config.c
index 47f0b98b707f8..f33a7e4ae917b 100644
--- a/fs/dlm/config.c
+++ b/fs/dlm/config.c
@@ -221,6 +221,7 @@ struct dlm_space {
 	struct list_head members;
 	struct mutex members_lock;
 	int members_count;
+	struct dlm_nodes *nds;
 };
 
 struct dlm_comms {
@@ -430,6 +431,7 @@ static struct config_group *make_space(struct config_group *g, const char *name)
 	INIT_LIST_HEAD(&sp->members);
 	mutex_init(&sp->members_lock);
 	sp->members_count = 0;
+	sp->nds = nds;
 	return &sp->group;
 
  fail:
@@ -451,6 +453,7 @@ static void drop_space(struct config_group *g, struct config_item *i)
 static void release_space(struct config_item *i)
 {
 	struct dlm_space *sp = config_item_to_space(i);
+	kfree(sp->nds);
 	kfree(sp);
 }
 
-- 
2.25.1