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 99EB6C32774 for ; Tue, 23 Aug 2022 08:18:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242780AbiHWISu (ORCPT ); Tue, 23 Aug 2022 04:18:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242162AbiHWIOD (ORCPT ); Tue, 23 Aug 2022 04:14:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 497276C74B; Tue, 23 Aug 2022 01:09:28 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C0187611DD; Tue, 23 Aug 2022 08:09:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF6E9C433D6; Tue, 23 Aug 2022 08:09:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661242167; bh=6aPiWU1DmthuuDEU+s0sTpbF8usqvd3MVqimuy22VTM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zUPCawR5rtI4Ut8XaSjIHgnB7o9iNrQ5xA3LA35iqau8D6sFTstADG63pjfvi8LHu Mqo/AivpFpgd8aEoEhJkpHh8s187lfryv881l/K8IJr/2YaQ8f4C4j8FHWyBoRiOsZ 4UMcutgsJAvRYeIFw/shi1773p6BGmcPKVV43hT0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+760a73552f47a8cd0fd9@syzkaller.appspotmail.com, Tetsuo Handa , Hou Wenlong , Sean Christopherson , Maxim Levitsky Subject: [PATCH 4.9 030/101] KVM: x86: Mark TSS busy during LTR emulation _after_ all fault checks Date: Tue, 23 Aug 2022 10:03:03 +0200 Message-Id: <20220823080035.739214317@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080034.579196046@linuxfoundation.org> References: <20220823080034.579196046@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: linux-kernel@vger.kernel.org From: Sean Christopherson commit ec6e4d863258d4bfb36d48d5e3ef68140234d688 upstream. Wait to mark the TSS as busy during LTR emulation until after all fault checks for the LTR have passed. Specifically, don't mark the TSS busy if the new TSS base is non-canonical. Opportunistically drop the one-off !seg_desc.PRESENT check for TR as the only reason for the early check was to avoid marking a !PRESENT TSS as busy, i.e. the common !PRESENT is now done before setting the busy bit. Fixes: e37a75a13cda ("KVM: x86: Emulator ignores LDTR/TR extended base on LLDT/LTR") Reported-by: syzbot+760a73552f47a8cd0fd9@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Cc: Tetsuo Handa Cc: Hou Wenlong Signed-off-by: Sean Christopherson Reviewed-by: Maxim Levitsky Link: https://lore.kernel.org/r/20220711232750.1092012-2-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/emulate.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1713,16 +1713,6 @@ static int __load_segment_descriptor(str case VCPU_SREG_TR: if (seg_desc.s || (seg_desc.type != 1 && seg_desc.type != 9)) goto exception; - if (!seg_desc.p) { - err_vec = NP_VECTOR; - goto exception; - } - old_desc = seg_desc; - seg_desc.type |= 2; /* busy */ - ret = ctxt->ops->cmpxchg_emulated(ctxt, desc_addr, &old_desc, &seg_desc, - sizeof(seg_desc), &ctxt->exception); - if (ret != X86EMUL_CONTINUE) - return ret; break; case VCPU_SREG_LDTR: if (seg_desc.s || seg_desc.type != 2) @@ -1763,6 +1753,15 @@ static int __load_segment_descriptor(str ((u64)base3 << 32))) return emulate_gp(ctxt, 0); } + + if (seg == VCPU_SREG_TR) { + old_desc = seg_desc; + seg_desc.type |= 2; /* busy */ + ret = ctxt->ops->cmpxchg_emulated(ctxt, desc_addr, &old_desc, &seg_desc, + sizeof(seg_desc), &ctxt->exception); + if (ret != X86EMUL_CONTINUE) + return ret; + } load: ctxt->ops->set_segment(ctxt, selector, &seg_desc, base3, seg); if (desc)