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b=mJzrii+QOLIMKzCo2P4idP+jnZNXCZcMi1F5VpU94H3aM1ll1eQR0kC36Amt9yleTqLNuPhIG2H4zKFOUXyhhZjpOHQ0yLWY14PFDQWdC3beNuqIZspXDL/WW/1TGiXCJg+9hoJhzHtJxWp92XAbzuBjUw1nRDuq9YdLBife0E8= Received: from BY5PR10MB4196.namprd10.prod.outlook.com (2603:10b6:a03:20d::23) by DM5PR10MB1786.namprd10.prod.outlook.com (2603:10b6:4:e::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4995.22; Fri, 18 Feb 2022 17:14:24 +0000 Received: from BY5PR10MB4196.namprd10.prod.outlook.com ([fe80::11f6:860e:575a:e6f1]) by BY5PR10MB4196.namprd10.prod.outlook.com ([fe80::11f6:860e:575a:e6f1%5]) with mapi id 15.20.4995.014; Fri, 18 Feb 2022 17:14:24 +0000 Message-ID: <8ba01b8b-6fe6-522e-5a56-28a4bf0c79d6@oracle.com> Date: Fri, 18 Feb 2022 09:14:21 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH] hugetlb: clean up potential spectre issue warnings Content-Language: en-US To: liuyuntao Cc: akpm@linux-foundation.org, baolin.wang@linux.alibaba.com, dan.carpenter@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, yaozhenguo1@gmail.com References: <20220217234218.192885-1-mike.kravetz@oracle.com> <20220218034025.17687-1-liuyuntao10@huawei.com> From: Mike Kravetz In-Reply-To: <20220218034025.17687-1-liuyuntao10@huawei.com> Content-Type: text/plain; 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dkim=pass header.d=oracle.com header.s=corp-2021-07-09 header.b=hARdYIp8; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=mJzrii+Q; dmarc=pass (policy=none) header.from=oracle.com; spf=none (imf16.hostedemail.com: domain of mike.kravetz@oracle.com has no SPF policy when checking 205.220.177.32) smtp.mailfrom=mike.kravetz@oracle.com X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 3392318000E X-Stat-Signature: 44w48p1nqh8wb6kagw3cpfowakus9cjf X-HE-Tag: 1645204595-721567 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2/17/22 19:40, liuyuntao wrote: > On 17 Feb 2022 15:42:18 -0800, Mike Kravetz wrote: >> Recently introduced code allows numa nodes to be specified on the >> kernel command line for hugetlb allocations or CMA reservations. The >> node values are user specified and used as indicies into arrays. This >> generated the following smatch warnings: >> >> mm/hugetlb.c:4170 hugepages_setup() warn: potential spectre issue 'default_hugepages_in_node' [w] >> mm/hugetlb.c:4172 hugepages_setup() warn: potential spectre issue 'parsed_hstate->max_huge_pages_node' [w] >> mm/hugetlb.c:6898 cmdline_parse_hugetlb_cma() warn: potential spectre issue 'hugetlb_cma_size_in_node' [w] (local cap) >> >> Clean up by using array_index_nospec to sanitize array indicies. >> >> Signed-off-by: Mike Kravetz >> --- >> mm/hugetlb.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index 1f0cca036f7f..6b14d0791cb4 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -31,6 +31,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -4161,7 +4162,7 @@ static int __init hugepages_setup(char *s) >> } >> if (tmp >= nr_online_nodes) >> goto invalid; >> - node = tmp; >> + node = array_index_nospec(tmp, nr_online_nodes); >> p += count + 1; >> /* Parse hugepages */ >> if (sscanf(p, "%lu%n", &tmp, &count) != 1) >> @@ -6889,9 +6890,9 @@ static int __init cmdline_parse_hugetlb_cma(char *p) >> break; >> >> if (s[count] == ':') { >> - nid = tmp; >> - if (nid < 0 || nid >= MAX_NUMNODES) >> + if (tmp < 0 || tmp >= MAX_NUMNODES) > > Here tmp is unsigned, no need to check if less than 0. Thanks! I shuffled the code a bit and missed this point. Actually, this routine cmdline_parse_hugetlb_cma has the same issue you addressed in [1]. I did not see that until now. It is fixed with this change. I will send a v2 with: - Remove check for unsigned tmp < 0 - Add a note in commit log that this also addresses an overflow truncation issue in the assignement of an unsigned long to int. [1] https://lore.kernel.org/linux-mm/20220209134018.8242-1-liuyuntao10@huawei.com/ -- Mike Kravetz