linux-kernel - [PATCH] mm/hugetlb: Fix potential double free in hugetlb_register

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Date:   Thu, 7 Jan 2021 07:32:49 -0500
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <mike.kravetz@...cle.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH] mm/hugetlb: Fix potential double free in hugetlb_register_node() error path

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().

Fixes: a3437870160c ("hugetlb: new sysfs interface")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Cc: <stable@...r.kernel.org>
---
 mm/hugetlb.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e249bffa0e75..91a2a2025a2c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2947,8 +2947,10 @@ 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;
 }
-- 
2.19.1