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From: Jingxiangfeng <jingxiangfeng@huawei.com>
To: <akpm@linux-foundation.org>
Cc: <mhocko@kernel.org>, <hughd@google.com>,
	<mike.kravetz@oracle.com>, <n-horiguchi@ah.jp.nec.com>,
	<aarcange@redhat.com>, <kirill.shutemov@linux.intel.com>,
	<linux-kernel@vger.kernel.org>,
	"Jing Xiangfeng" <jingxiangfeng@huawei.com>
Subject: [PATCH] mm/hugetlb: Fix unsigned overflow in __nr_hugepages_store_common()
Date: Sat, 16 Feb 2019 21:31:12 +0800	[thread overview]
Message-ID: <1550323872-119049-1-git-send-email-jingxiangfeng@huawei.com> (raw)

From: Jing Xiangfeng <jingxiangfeng@huawei.com>

We can use the following command to dynamically allocate huge pages:
	echo NR_HUGEPAGES > /proc/sys/vm/nr_hugepages
The count in  __nr_hugepages_store_common() is parsed from /proc/sys/vm/nr_hugepages,
The maximum number of count is ULONG_MAX,
the operation 'count += h->nr_huge_pages - h->nr_huge_pages_node[nid]' overflow and count will be a wrong number.
So check the overflow to fix this problem.

Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com>
---
 mm/hugetlb.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index afef616..55173c3 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2423,7 +2423,12 @@ static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
 		 * per node hstate attribute: adjust count to global,
 		 * but restrict alloc/free to the specified node.
 		 */
+		unsigned long old_count = count;
 		count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
+		if (count < old_count) {
+			err = -EINVAL;
+			goto out;
+		}
 		init_nodemask_of_node(nodes_allowed, nid);
 	} else
 		nodes_allowed = &node_states[N_MEMORY];
-- 
2.7.4


             reply	other threads:[~2019-02-16 13:35 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-16 13:31 Jingxiangfeng [this message]
2019-02-18  9:27 ` [PATCH] mm/hugetlb: Fix unsigned overflow in __nr_hugepages_store_common() Michal Hocko
2019-02-19 23:45   ` Mike Kravetz
2019-02-22  6:10     ` Jing Xiangfeng

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