From nobody Mon Sep 29 21:14:57 2025 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 5730CC00140 for ; Mon, 15 Aug 2022 21:54:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343539AbiHOVyB (ORCPT ); Mon, 15 Aug 2022 17:54:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350462AbiHOVvX (ORCPT ); Mon, 15 Aug 2022 17:51:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 50E36105230; Mon, 15 Aug 2022 12:32:38 -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 2C81D60FBE; Mon, 15 Aug 2022 19:32:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2812CC433C1; Mon, 15 Aug 2022 19:32:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660591957; bh=0qhytQhAGsmyQiX8PjVBdYkViWXICbwq786/9Rnsrzk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SEx/UWQgyva4tIR4nv9zgCB2JR6tdaoKmIlMjJJQKXP8mq/B7oR0S2g9IH59xaTGR 2CVJnB48H9izbRAl3tgoqfjsfoRdVMrs5dNQvSq3zgPqQY6ZPmFsyA0XXZvfl+gnjB umPPARdodkdz5w6gkVjhHBr3ph+qKfBHsEpC2chY= 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 5.19 0036/1157] KVM: x86: Mark TSS busy during LTR emulation _after_ all fault checks Date: Mon, 15 Aug 2022 19:49:52 +0200 Message-Id: <20220815180440.879143269@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180439.416659447@linuxfoundation.org> References: <20220815180439.416659447@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 L= LDT/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 @@ -1687,16 +1687,6 @@ static int __load_segment_descriptor(str case VCPU_SREG_TR: if (seg_desc.s || (seg_desc.type !=3D 1 && seg_desc.type !=3D 9)) goto exception; - if (!seg_desc.p) { - err_vec =3D NP_VECTOR; - goto exception; - } - old_desc =3D seg_desc; - seg_desc.type |=3D 2; /* busy */ - ret =3D ctxt->ops->cmpxchg_emulated(ctxt, desc_addr, &old_desc, &seg_des= c, - sizeof(seg_desc), &ctxt->exception); - if (ret !=3D X86EMUL_CONTINUE) - return ret; break; case VCPU_SREG_LDTR: if (seg_desc.s || seg_desc.type !=3D 2) @@ -1737,6 +1727,15 @@ static int __load_segment_descriptor(str ((u64)base3 << 32), ctxt)) return emulate_gp(ctxt, 0); } + + if (seg =3D=3D VCPU_SREG_TR) { + old_desc =3D seg_desc; + seg_desc.type |=3D 2; /* busy */ + ret =3D ctxt->ops->cmpxchg_emulated(ctxt, desc_addr, &old_desc, &seg_des= c, + sizeof(seg_desc), &ctxt->exception); + if (ret !=3D X86EMUL_CONTINUE) + return ret; + } load: ctxt->ops->set_segment(ctxt, selector, &seg_desc, base3, seg); if (desc)