linux-kernel - [PATCH] hugetlbfs: fix a truncation issue in hugepages parameter

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Date:   Wed, 9 Feb 2022 21:40:18 +0800
From:   liuyuntao <liuyuntao10@...wei.com>
To:     <mike.kravetz@...cle.com>, <akpm@...ux-foundation.org>,
        <yaozhenguo1@...il.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <wuxu.wu@...wei.com>, <fangchuangchuang@...wei.com>,
        <windspectator@...il.com>
Subject: [PATCH] hugetlbfs: fix a truncation issue in hugepages parameter

From: Liu Yuntao <liuyuntao10@...wei.com>

When we specify a large number for node in hugepages parameter,
it may be parsed to another number due to truncation in this statement:
	node = tmp;

For example, add following parameter in command line:
	hugepagesz=1G hugepages=4294967297:5
and kernel will allocate 5 hugepages for node 1 instead of ignoring it.

I move the validation check earlier to fix this issue, and slightly
simplifies the condition here.

Fixes: b5389086ad7be0 ("hugetlbfs: extend the definition of hugepages parameter to support node allocation")
Signed-off-by: Liu Yuntao <liuyuntao10@...wei.com>
---
 mm/hugetlb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 61895cc01d09..0929547f6ad6 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4159,10 +4159,10 @@ static int __init hugepages_setup(char *s)
 				pr_warn("HugeTLB: architecture can't support node specific alloc, ignoring!\n");
 				return 0;
 			}
+			if (tmp >= nr_online_nodes)
+				goto invalid;
 			node = tmp;
 			p += count + 1;
-			if (node < 0 || node >= nr_online_nodes)
-				goto invalid;
 			/* Parse hugepages */
 			if (sscanf(p, "%lu%n", &tmp, &count) != 1)
 				goto invalid;
-- 
2.33.0