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 3BFE6C433EF for ; Tue, 19 Jul 2022 12:33:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240416AbiGSMdm (ORCPT ); Tue, 19 Jul 2022 08:33:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233786AbiGSMdI (ORCPT ); Tue, 19 Jul 2022 08:33:08 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6BEDB7358B; Tue, 19 Jul 2022 05:12:38 -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 ams.source.kernel.org (Postfix) with ESMTPS id C54FFB81B1A; Tue, 19 Jul 2022 12:12:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35156C341CF; Tue, 19 Jul 2022 12:12:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658232756; bh=E2/fWrdznifDX8AkHMSJOC4G5mDAciLTGgAmMjUvb4c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nyx8t9VmFbuyJGBbeOO/xOLBqO1wFm3pTC943WfiaZlDnua5/g+1Zx4fcbCNiyBu5 NLx/U3tuiQ+tehUa70yeGHbl3cpPDdZc9PEELpsTmx1eKYpeyP6irz7zI/2Vw8+cID 1bbno/eLdlfCm9VBIL1iFXK5HXyKjMIsYtRoFr7o= 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 5.15 055/167] sysctl: Fix data races in proc_doulongvec_minmax(). Date: Tue, 19 Jul 2022 13:53:07 +0200 Message-Id: <20220719114701.918591935@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220719114656.750574879@linuxfoundation.org> References: <20220719114656.750574879@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 c31bcc8fb89fc2812663900589c6325ba35d9a65 ] 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_doulongvec_minmax() to use READ_ONCE() and WRITE_ONCE() internally to fix data-races on the sysctl side. For now, proc_doulongvec_minmax() 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 | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index bdb2f17b723f..9a68da5e1551 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1281,9 +1281,9 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, err = -EINVAL; break; } - *i = val; + WRITE_ONCE(*i, val); } else { - val = convdiv * (*i) / convmul; + val = convdiv * READ_ONCE(*i) / convmul; if (!first) proc_put_char(&buffer, &left, '\t'); proc_put_long(&buffer, &left, val, false); -- 2.35.1