linux-kernel - [PATCH] ocfs2: possible memory leak in mlog_sys

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Date:   Tue, 18 Oct 2022 15:52:13 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <ocfs2-devel@....oracle.com>
CC:     <mark@...heh.com>, <jlbec@...lplan.org>,
        <joseph.qi@...ux.alibaba.com>, <gregkh@...uxfoundation.org>,
        <akpm@...ux-foundation.org>
Subject: [PATCH] ocfs2: possible memory leak in mlog_sys_init()

Inject fault while probing module, kset_register() may fail,
if it fails, but the refcount of kobject is not decreased to
0, the name allocated in kobject_set_name() is leaked. Fix
this by calling kset_put(), so that name can be freed in
callback function kobject_cleanup().

unreferenced object 0xffff888100da9348 (size 8):
  comm "modprobe", pid 257, jiffies 4294701096 (age 33.334s)
  hex dump (first 8 bytes):
    6c 6f 67 6d 61 73 6b 00                          logmask.
  backtrace:
    [<00000000306e441c>] __kmalloc_node_track_caller+0x44/0x1b0
    [<000000007c491a9e>] kstrdup+0x3a/0x70
    [<0000000015719a3b>] kstrdup_const+0x63/0x80
    [<0000000084e458ea>] kvasprintf_const+0x149/0x180
    [<0000000091302b42>] kobject_set_name_vargs+0x56/0x150
    [<000000005f48eeac>] kobject_set_name+0xab/0xe0

Fixes: 34980ca8faeb ("Drivers: clean up direct setting of the name of a kset")
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
 fs/ocfs2/cluster/masklog.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/cluster/masklog.c b/fs/ocfs2/cluster/masklog.c
index 563881ddbf00..7f9ba816d955 100644
--- a/fs/ocfs2/cluster/masklog.c
+++ b/fs/ocfs2/cluster/masklog.c
@@ -156,6 +156,7 @@ static struct kset mlog_kset = {
 int mlog_sys_init(struct kset *o2cb_kset)
 {
 	int i = 0;
+	int ret;
 
 	while (mlog_attrs[i].attr.mode) {
 		mlog_default_attrs[i] = &mlog_attrs[i].attr;
@@ -165,7 +166,11 @@ int mlog_sys_init(struct kset *o2cb_kset)
 
 	kobject_set_name(&mlog_kset.kobj, "logmask");
 	mlog_kset.kobj.kset = o2cb_kset;
-	return kset_register(&mlog_kset);
+	ret = kset_register(&mlog_kset);
+	if (ret)
+		kset_put(&mlog_kset);
+
+	return ret;
 }
 
 void mlog_sys_shutdown(void)
-- 
2.25.1