From mboxrd@z Thu Jan 1 00:00:00 1970 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 23192CCA47F for ; Tue, 19 Jul 2022 12:55:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241907AbiGSMzf (ORCPT ); Tue, 19 Jul 2022 08:55:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40384 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242382AbiGSMy3 (ORCPT ); Tue, 19 Jul 2022 08:54:29 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D1C797497; Tue, 19 Jul 2022 05:21:36 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id F1107618D1; Tue, 19 Jul 2022 12:21:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC9B4C341C6; Tue, 19 Jul 2022 12:21:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658233295; bh=8GkFOcfHZQJAUdibGRDiaFGXNy8Bo9/QPv0FyUulaz8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=f29ldv8Zrwy2sK0R2NVcrQ1CucoEpki9wjjK+hM5lQscV70yX8jWyq0IQbfrMHoh1 z3M9UkvItwxIKaHW4t6ck+4pWN2UZ+AKVev/Z63/31CEfEZ6xDSBFxxObA2XzUZ8Qs cKQk+HgcRPSZFH8J2dlkrywqFf36IaN98W53lNCs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kuniyuki Iwashima , "David S. Miller" , Sasha Levin Subject: [PATCH 5.18 074/231] sysctl: Fix data races in proc_dointvec_jiffies(). Date: Tue, 19 Jul 2022 13:52:39 +0200 Message-Id: <20220719114720.932750685@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220719114714.247441733@linuxfoundation.org> References: <20220719114714.247441733@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kuniyuki Iwashima [ Upstream commit e877820877663fbae8cb9582ea597a7230b94df3 ] 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 Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- kernel/sysctl.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 7a8899f237a2..878b1122cb89 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1245,9 +1245,12 @@ 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; -- 2.35.1