From patchwork Wed Jul 6 23:39:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuniyuki Iwashima X-Patchwork-Id: 12908912 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3DEBCCA480 for ; Wed, 6 Jul 2022 23:42:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234184AbiGFXmy (ORCPT ); Wed, 6 Jul 2022 19:42:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234870AbiGFXmO (ORCPT ); Wed, 6 Jul 2022 19:42:14 -0400 Received: from smtp-fw-6001.amazon.com (smtp-fw-6001.amazon.com [52.95.48.154]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8D28E2DA83; Wed, 6 Jul 2022 16:42:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1657150929; x=1688686929; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=YKlh3xU99+PnvB8tm4pVIMQEaPxMo6bcMnrjqauDi48=; b=BZ57ceqbL7CzekeOmV5oMc3mER3nSQxqoUSTVHBcy7bgFLyI0EPHqr6I Rth7rv0wsAw2wJae/s3B/VbAaDxwlKFJxtolKszErOPc7stSyX/VU82r7 2rhGjTw8QOM4lSkzuwioYkkYonLNoCmN1LFjgMRIAuHJ4HARjPPisGlgA A=; Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-iad-1e-f771ae83.us-east-1.amazon.com) ([10.43.8.6]) by smtp-border-fw-6001.iad6.amazon.com with ESMTP; 06 Jul 2022 23:42:08 +0000 Received: from EX13MTAUWB001.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan2.iad.amazon.com [10.40.163.34]) by email-inbound-relay-iad-1e-f771ae83.us-east-1.amazon.com (Postfix) with ESMTPS id 519F81216E0; Wed, 6 Jul 2022 23:42:05 +0000 (UTC) Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX13MTAUWB001.ant.amazon.com (10.43.161.207) with Microsoft SMTP Server (TLS) id 15.0.1497.36; Wed, 6 Jul 2022 23:42:04 +0000 Received: from 88665a182662.ant.amazon.com (10.43.160.106) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1118.9; Wed, 6 Jul 2022 23:42:01 +0000 From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Luis Chamberlain , Kees Cook , Iurii Zaikin CC: Kuniyuki Iwashima , Kuniyuki Iwashima , , Subject: [PATCH v2 net 06/12] sysctl: Fix data races in proc_dointvec_jiffies(). Date: Wed, 6 Jul 2022 16:39:57 -0700 Message-ID: <20220706234003.66760-7-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220706234003.66760-1-kuniyu@amazon.com> References: <20220706234003.66760-1-kuniyu@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.43.160.106] X-ClientProxiedBy: EX13D36UWB001.ant.amazon.com (10.43.161.84) To EX19D004ANA001.ant.amazon.com (10.37.240.138) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org A sysctl variable is accessed concurrently, and there is always a chance of data-race. So, all readers and writers need some basic protection to avoid load/store-tearing. This patch changes proc_dointvec_jiffies() to use READ_ONCE() and WRITE_ONCE() internally to fix data-races on the sysctl side. For now, proc_dointvec_jiffies() itself is tolerant to a data-race, but we still need to add annotations on the other subsystem's side. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima --- kernel/sysctl.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 8c55ba01f41b..bf9383d17e1b 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1173,9 +1173,12 @@ static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *lvalp, if (write) { if (*lvalp > INT_MAX / HZ) return 1; - *valp = *negp ? -(*lvalp*HZ) : (*lvalp*HZ); + if (*negp) + WRITE_ONCE(*valp, -*lvalp * HZ); + else + WRITE_ONCE(*valp, *lvalp * HZ); } else { - int val = *valp; + int val = READ_ONCE(*valp); unsigned long lval; if (val < 0) { *negp = true;