hugetlbfs: fix a truncation issue in hugepages parameter

mainline inclusion
from mainline-v5.17-rc6
commit e79ce983
category: bugfix
bugzilla: 186043, https://gitee.com/openeuler/kernel/issues/I518AB
CVE: NA

-----------------------------------

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.

Link: https://lkml.kernel.org/r/20220209134018.8242-1-liuyuntao10@huawei.com
Fixes: b5389086 ("hugetlbfs: extend the definition of hugepages parameter to support node allocation")
Signed-off-by: NLiu Yuntao <liuyuntao10@huawei.com>
Reviewed-by: NMike Kravetz <mike.kravetz@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NLiu Shixin <liushixin2@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

mm/hugetlb.c

@@ -3600,10 +3600,10 @@ 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;