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=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 005F0C38A29 for ; Sat, 18 Apr 2020 14:55:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C891B21D82 for ; Sat, 18 Apr 2020 14:55:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587221704; bh=1pQapq9m3603xrXiSN4BF3wGZPcBk5uTiJAJZ3h1E+A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=bjYm8C/0/fjR9s3lOmGACu8rd4raIApKDJPYGBCt9LywKjZS7OHqFughTMsPpIk40 T3cnVK4BfcxdIgCryqYH0YJ02q5zLjfPYiJsQNnEkWLR8FcBfim7c5fRmpEm4okqjZ oDs9Xsjg0UzhZXBRpP+XQjRaycc1tHWMPXH0AJ30= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728940AbgDROzD (ORCPT ); Sat, 18 Apr 2020 10:55:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:50520 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727941AbgDROlZ (ORCPT ); Sat, 18 Apr 2020 10:41:25 -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 D2F5022245; Sat, 18 Apr 2020 14:41:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587220884; bh=1pQapq9m3603xrXiSN4BF3wGZPcBk5uTiJAJZ3h1E+A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0gZwiUwX+lnUePDlCUvK/58P+QNHuI8fpL+Peh5H7INT0o7NCqw3KMH26VSl2uJZi KtU8rDLGjNwQrdeV1j50ifyxfxQ886gExMgZt14cUKuIoViyQCon8HcfJYrNicQ6JA L5XL8viEoOkStdm+0XCvJYZwruhAyotpsJTbOmPY= 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 5.4 29/78] KVM: s390: vsie: Fix possible race when shadowing region 3 tables Date: Sat, 18 Apr 2020 10:39:58 -0400 Message-Id: <20200418144047.9013-29-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200418144047.9013-1-sashal@kernel.org> References: <20200418144047.9013-1-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