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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 C58B0C2BA19 for ; Wed, 15 Apr 2020 13:04:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 971F220775 for ; Wed, 15 Apr 2020 13:04:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586955855; bh=1pQapq9m3603xrXiSN4BF3wGZPcBk5uTiJAJZ3h1E+A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=oIMFBL2hcfpzbbmzNmXePJKZOxfxj8uBvyzLh+Vcp4kORfhhWsijjCjqWRbwWQrIF tr6A2MSKRUqCeY8WD6HxQELtyB4M9lRuief7L7p936fwgHlKUzVzlhOHSGoM4VQiXG XVyqYLiLMJJAwdZTyBGqwNnMPZuYzlhJIPrC9kQQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2505835AbgDONEL (ORCPT ); Wed, 15 Apr 2020 09:04:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:56204 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2897143AbgDOLg0 (ORCPT ); Wed, 15 Apr 2020 07:36:26 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E76D0208FE; Wed, 15 Apr 2020 11:36:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586950584; bh=1pQapq9m3603xrXiSN4BF3wGZPcBk5uTiJAJZ3h1E+A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=g3MkuLRURQYK3wsH+aKZbj/stfmM7GbXJu+V6qRGnmTL8hxyj1YCPuhoAwO24IsZ2 C0uOn9Wcwfh3P+WdRAw318CQ5bxQccLpfHXvXvT7VPnJ0NUmh6psWgfM59XoSSPIew OjO2guO7scPxidOXGG09Smd/ikxxeOPf61tzLs9k= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: David Hildenbrand , Claudio Imbrenda , Christian Borntraeger , Sasha Levin , kvm@vger.kernel.org, linux-s390@vger.kernel.org Subject: [PATCH AUTOSEL 5.6 083/129] KVM: s390: vsie: Fix possible race when shadowing region 3 tables Date: Wed, 15 Apr 2020 07:33:58 -0400 Message-Id: <20200415113445.11881-83-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200415113445.11881-1-sashal@kernel.org> References: <20200415113445.11881-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 edcdca97e85ee..06d602c5ec7b7 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -1840,6 +1840,7 @@ 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