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 X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52E54C4360F for ; Tue, 19 Mar 2019 08:33:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 257EC2075E for ; Tue, 19 Mar 2019 08:33:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552984401; bh=jjSqJUBachI3OkoOnRR731pkIsic5VXZ2MyMB0BSh8w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=C7Nh2n3bh4a7amZR1cKirnxhZIOfUrXxaIxBjYyjIA27CEDtnfciHcBSb6Xo4T2Tm I0/qxhO1gGiLKHBDBh3cKRjqh2DCnOBxlyZ6Np66fpthcY5MpTlCLYFwbTny8K/kkX 3+q4Tq5tJieA5jrxddSAH3W66/wv2y+KXEgPjUWU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727407AbfCSIdU (ORCPT ); Tue, 19 Mar 2019 04:33:20 -0400 Received: from mx2.suse.de ([195.135.220.15]:32962 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725978AbfCSIdT (ORCPT ); Tue, 19 Mar 2019 04:33:19 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 43236AFDF; Tue, 19 Mar 2019 08:33:18 +0000 (UTC) Date: Tue, 19 Mar 2019 09:33:16 +0100 From: Michal Hocko To: Jann Horn Cc: James Morris , "Serge E. Hallyn" , Tejun Heo , Li Zefan , Johannes Weiner , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Aristeu Rozanski , "Serge E . Hallyn" , cgroups@vger.kernel.org Subject: Re: [PATCH] device_cgroup: fix RCU imbalance in error case Message-ID: <20190319083316.GQ8924@dhcp22.suse.cz> References: <20190319013659.86199-1-jannh@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190319013659.86199-1-jannh@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 19-03-19 02:36:59, Jann Horn wrote: > When dev_exception_add() returns an error (due to a failed memory > allocation), make sure that we move the RCU preemption count back to where > it was before we were called. We dropped the RCU read lock inside the loop > body, so we can't just "break". > > sparse complains about this, too: > > $ make -s C=2 security/device_cgroup.o > ./include/linux/rcupdate.h:647:9: warning: context imbalance in > 'propagate_exception' - unexpected unlock > > Fixes: d591fb56618f ("device_cgroup: simplify cgroup tree walk in propagate_exception()") > Cc: stable@vger.kernel.org > Signed-off-by: Jann Horn FWIW looks good to me. Acked-by: Michal Hocko Thanks > --- > Compile-tested only. > > I'm not entirely sure who's supposed to be the maintainer for this thing. > The sign-offs on the commits to this file come from Tejun, but MAINTAINERS > claims it's part of security/, so I'm just sending this to both the > security folks and the cgroup folks, you can figure out whose tree you want > to take this through. :P > If the cgroup folks feel responsible for this file, maybe you could fix up > MAINTAINERS? > > security/device_cgroup.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/security/device_cgroup.c b/security/device_cgroup.c > index cd97929fac66..dc28914fa72e 100644 > --- a/security/device_cgroup.c > +++ b/security/device_cgroup.c > @@ -560,7 +560,7 @@ static int propagate_exception(struct dev_cgroup *devcg_root, > devcg->behavior == DEVCG_DEFAULT_ALLOW) { > rc = dev_exception_add(devcg, ex); > if (rc) > - break; > + return rc; > } else { > /* > * in the other possible cases: > -- > 2.21.0.225.g810b269d1ac-goog -- Michal Hocko SUSE Labs