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 9BA9FEB64D9 for ; Mon, 19 Jun 2023 10:58:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232476AbjFSK6s (ORCPT ); Mon, 19 Jun 2023 06:58:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232030AbjFSK6b (ORCPT ); Mon, 19 Jun 2023 06:58:31 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67F0F10F3 for ; Mon, 19 Jun 2023 03:56:43 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 059A460A4D for ; Mon, 19 Jun 2023 10:56:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D5F7C433C0; Mon, 19 Jun 2023 10:56:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1687172202; bh=EKZylMj1LczZsez8Yj0cqowH/+6VPMXA/Kin/w/466k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E7EReSp6Mb8ytQoQuV6I1qPkW47uJC6NMYlMTxcbMGAjBB84TrTrZY97rndYxlZLj XKilCEB9yjZ0aAdSqm1fP/wTdq1e1yAGY59FP5Vabv2OntAWA9Yu0VsLIa6qrX9CmJ W6VJKGTUcdKHujCKkLpiTZwdmla/f94lvAeh89G0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, John Sperbeck , Tejun Heo , "T.J. Mercier" Subject: [PATCH 5.10 74/89] cgroup: always put cset in cgroup_css_set_put_fork Date: Mon, 19 Jun 2023 12:31:02 +0200 Message-ID: <20230619102141.628803408@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230619102138.279161276@linuxfoundation.org> References: <20230619102138.279161276@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: John Sperbeck commit 2bd110339288c18823dcace602b63b0d8627e520 upstream. A successful call to cgroup_css_set_fork() will always have taken a ref on kargs->cset (regardless of CLONE_INTO_CGROUP), so always do a corresponding put in cgroup_css_set_put_fork(). Without this, a cset and its contained css structures will be leaked for some fork failures. The following script reproduces the leak for a fork failure due to exceeding pids.max in the pids controller. A similar thing can happen if we jump to the bad_fork_cancel_cgroup label in copy_process(). [ -z "$1" ] && echo "Usage $0 pids-root" && exit 1 PID_ROOT=$1 CGROUP=$PID_ROOT/foo [ -e $CGROUP ] && rmdir -f $CGROUP mkdir $CGROUP echo 5 > $CGROUP/pids.max echo $$ > $CGROUP/cgroup.procs fork_bomb() { set -e for i in $(seq 10); do /bin/sleep 3600 & done } (fork_bomb) & wait echo $$ > $PID_ROOT/cgroup.procs kill $(cat $CGROUP/cgroup.procs) rmdir $CGROUP Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups") Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: John Sperbeck Signed-off-by: Tejun Heo [TJM: This backport accommodates the lack of cgroup_unlock] Signed-off-by: T.J. Mercier Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup/cgroup.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -6138,19 +6138,18 @@ err: static void cgroup_css_set_put_fork(struct kernel_clone_args *kargs) __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex) { + struct cgroup *cgrp = kargs->cgrp; + struct css_set *cset = kargs->cset; + cgroup_threadgroup_change_end(current); - if (kargs->flags & CLONE_INTO_CGROUP) { - struct cgroup *cgrp = kargs->cgrp; - struct css_set *cset = kargs->cset; + if (cset) { + put_css_set(cset); + kargs->cset = NULL; + } + if (kargs->flags & CLONE_INTO_CGROUP) { mutex_unlock(&cgroup_mutex); - - if (cset) { - put_css_set(cset); - kargs->cset = NULL; - } - if (cgrp) { cgroup_put(cgrp); kargs->cgrp = NULL;