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 5981AC43334 for ; Tue, 19 Jul 2022 12:36:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240857AbiGSMgv (ORCPT ); Tue, 19 Jul 2022 08:36:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240706AbiGSMgI (ORCPT ); Tue, 19 Jul 2022 08:36:08 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B964D7AC14; Tue, 19 Jul 2022 05:14:07 -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 56F7761772; Tue, 19 Jul 2022 12:13:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34269C341C6; Tue, 19 Jul 2022 12:13:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658232805; bh=nZL5sHt4z6CkfvITyzjGV+EKz5h652UKzG19cc6+3GU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jjcwpSkIy4ikk3UsvmxNjHXFy1AR+Xu91RQqtWGWKfM/FJuccMuRK2FK7UfqCEDuW 5byMWaL7jisTcSC6oSQIrNgYlccokjpXFQCqGNyrdLdZFbRr15mT+1i3KSzmUtX3sq bbXanOYyfKgDMN/XATcDswqvgCV/guDAEH/QJFUY= 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 5.15 051/167] sysctl: Fix data races in proc_dointvec(). Date: Tue, 19 Jul 2022 13:53:03 +0200 Message-Id: <20220719114701.539279926@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 1f1be04b4d48a2475ea1aab46a99221bfc5c0968 ] 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() to use READ_ONCE() and WRITE_ONCE() internally to fix data-races on the sysctl side. For now, proc_dointvec() 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 | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 0586047f7323..11f0714273ab 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -566,14 +566,14 @@ static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp, if (*negp) { if (*lvalp > (unsigned long) INT_MAX + 1) return -EINVAL; - *valp = -*lvalp; + WRITE_ONCE(*valp, -*lvalp); } else { if (*lvalp > (unsigned long) INT_MAX) return -EINVAL; - *valp = *lvalp; + WRITE_ONCE(*valp, *lvalp); } } else { - int val = *valp; + int val = READ_ONCE(*valp); if (val < 0) { *negp = true; *lvalp = -(unsigned long)val; -- 2.35.1