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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 1357AC55186 for ; Wed, 22 Apr 2020 10:15:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C65422071E for ; Wed, 22 Apr 2020 10:15:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587550524; bh=QcxIIkU7Xer+34tSxnekSWV/PfKKYI/zglTQy48awg0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=U9hCrxUiH3P+w7xmuVOWFupFAHj6cmuF9Tgx8XM5gRFOuU/p2hHddIJiyouCsMp12 S2cmbr9fb7BKuWDIha5o4UqszMTnBwdI0PjXZQWS2R8NEF87pRWBvRdav94FxaWuzd nrjJh3zp2Voo+0wq7mkb6d26WL7r6ELGURnu5DOE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729651AbgDVKPT (ORCPT ); Wed, 22 Apr 2020 06:15:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:50160 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729627AbgDVKPF (ORCPT ); Wed, 22 Apr 2020 06:15:05 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F26C52071E; Wed, 22 Apr 2020 10:15:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587550504; bh=QcxIIkU7Xer+34tSxnekSWV/PfKKYI/zglTQy48awg0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jQMvqAhNur4thdNIKe/2oz3RqHoOJOOIJCUUitb1Cg+h4MFaxWbBjHwspGIWfViT3 QLLjFoy9dJSyR7qwZAplYE35kxs3ixa88M1XG2u5Wi65xCBJfIVS3orBhMPD5Eyy/P geqVn9oJRlN39IKr1aXXBdQ36ra2vE0GfVkGls8k= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Hildenbrand , Claudio Imbrenda , Christian Borntraeger , Sasha Levin Subject: [PATCH 4.19 42/64] KVM: s390: vsie: Fix possible race when shadowing region 3 tables Date: Wed, 22 Apr 2020 11:57:26 +0200 Message-Id: <20200422095020.408502552@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200422095008.799686511@linuxfoundation.org> References: <20200422095008.799686511@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Hildenbrand [ Upstream commit 1493e0f944f3c319d11e067c185c904d01c17ae5 ] We have to properly retry again by returning -EINVAL immediately in case somebody else instantiated the table concurrently. We missed to add the goto in this function only. The code now matches the other, similar shadowing functions. We are overwriting an existing region 2 table entry. All allocated pages are added to the crst_list to be freed later, so they are not lost forever. However, when unshadowing the region 2 table, we wouldn't trigger unshadowing of the original shadowed region 3 table that we replaced. It would get unshadowed when the original region 3 table is modified. As it's not connected to the page table hierarchy anymore, it's not going to get used anymore. However, for a limited time, this page table will stick around, so it's in some sense a temporary memory leak. Identified by manual code inspection. I don't think this classifies as stable material. Fixes: 998f637cc4b9 ("s390/mm: avoid races on region/segment/page table shadowing") Signed-off-by: David Hildenbrand Link: https://lore.kernel.org/r/20200403153050.20569-4-david@redhat.com Reviewed-by: Claudio Imbrenda Reviewed-by: Christian Borntraeger Signed-off-by: Christian Borntraeger Signed-off-by: Sasha Levin --- arch/s390/mm/gmap.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index b56c4fdb15178..7cde0f2f52e14 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -1838,6 +1838,7 @@ int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t, goto out_free; } else if (*table & _REGION_ENTRY_ORIGIN) { rc = -EAGAIN; /* Race with shadow */ + goto out_free; } crst_table_init(s_r3t, _REGION3_ENTRY_EMPTY); /* mark as invalid as long as the parent table is not protected */ -- 2.20.1