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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, Miaohe Lin <linmiaohe@huawei.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <smuchun@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 228/340] mm/hugetlb: fix potential double free in hugetlb_register_node() error path
Date:   Mon,  1 Mar 2021 17:12:52 +0100
Message-Id: <20210301161059.522897968@linuxfoundation.org>
In-Reply-To: <20210301161048.294656001@linuxfoundation.org>
References: <20210301161048.294656001@linuxfoundation.org>
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From: Miaohe Lin <linmiaohe@huawei.com>

[ Upstream commit cc2205a67dec5a700227a693fc113441e73e4641 ]

In hugetlb_sysfs_add_hstate(), we would do kobject_put() on hstate_kobjs
when failed to create sysfs group but forget to set hstate_kobjs to NULL.
Then in hugetlb_register_node() error path, we may free it again via
hugetlb_unregister_node().

Link: https://lkml.kernel.org/r/20210107123249.36964-1-linmiaohe@huawei.com
Fixes: a3437870160c ("hugetlb: new sysfs interface")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <smuchun@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/hugetlb.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d5b03b9262d4f..2e2527c9f9a21 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2812,8 +2812,10 @@ static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
 		return -ENOMEM;
 
 	retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
-	if (retval)
+	if (retval) {
 		kobject_put(hstate_kobjs[hi]);
+		hstate_kobjs[hi] = NULL;
+	}
 
 	return retval;
 }
-- 
2.27.0