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 34433C433EF for ; Tue, 19 Jul 2022 12:56:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242190AbiGSMz7 (ORCPT ); Tue, 19 Jul 2022 08:55:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242405AbiGSMyb (ORCPT ); Tue, 19 Jul 2022 08:54:31 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37B6E97487; Tue, 19 Jul 2022 05:21:34 -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 097066177D; Tue, 19 Jul 2022 12:21:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DFEEBC341D2; Tue, 19 Jul 2022 12:21:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658233292; bh=F3A7SXHYjof7BlkLaf1dpEJWq0dRZbv4zt/6zVtRX98=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nemFESH4bgiGA4WZbRuNJTKMsS3lswaZ5y4aRJ7pEYaJxfWvhsOa6ssHQQF0BJDO/ x1bZvBE0NIe79an+Z2ImiDVsLhQWbrmkGb7ea1lmBeu6mCI2wpNSHuFmRYcoyg6+Zu Pq8il7ip0XGF2qSSGdyIm05j5DcSkYp5k5cqRHqI= 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 5.18 073/231] sysctl: Fix data races in proc_doulongvec_minmax(). Date: Tue, 19 Jul 2022 13:52:38 +0200 Message-Id: <20220719114720.843625906@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 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 a769f64a78ed..7a8899f237a2 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1162,9 +1162,9 @@ 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