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dkim=pass header.d=oracle.com header.s=corp-2021-07-09 header.b=j59b4xX7; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=nS3Y0cnL; spf=none (imf18.hostedemail.com: domain of dan.carpenter@oracle.com has no SPF policy when checking 205.220.165.32) smtp.mailfrom=dan.carpenter@oracle.com; dmarc=pass (policy=none) header.from=oracle.com X-Rspam-User: X-HE-Tag: 1645547808-401966 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 Tue, Feb 22, 2022 at 04:15:45PM +0000, Schaufler, Casey wrote: > > -----Original Message----- > > From: Michal Hocko > > Sent: Monday, February 21, 2022 11:48 PM > > To: Mike Kravetz > > Cc: linux-mm@kvack.org; linux-kernel@vger.kernel.org; Baolin Wang > > ; Zhenguo Yao > > ; Liu Yuntao ; Dan > > Carpenter ; Andrew Morton > foundation.org> > > Subject: Re: [PATCH v2] hugetlb: clean up potential spectre issue warnings > > > > On Mon 21-02-22 12:24:25, Mike Kravetz wrote: > > > On 2/21/22 00:42, Michal Hocko wrote: > > > > On Fri 18-02-22 13:29:46, Mike Kravetz wrote: > > > > [...] > > > >> @@ -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 >= MAX_NUMNODES) > > > >> break; > > > >> + nid = array_index_nospec(tmp, MAX_NUMNODES); > > > >> > > > >> s += count + 1; > > > >> tmp = memparse(s, &s); > > > > > > > > This is an early boot code, how is this supposed to be used as a side > > > > channel? > > > > > > I do not have an evil hacker mind, but I can not think of a way this one time > > > use of a user specified index could be an issue. It does add noise to the > > > BUILD REGRESSION emails sent to Andrew. > > > > Maybe Smack can be taught to ignore __init and other early boot > > functions. > > Why is Smack getting called out? The relationship is not obvious. > He meant Smatch. It's a really common mistake that I did not anticipate in 2002. I can probably silence the spectre warnings for __init functions. TBH, I don't really understand spectre at all so I mostly ignore those warnings. :/ regards, dan carpenter