From nobody Tue Feb 10 14:49:26 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1507591075196372.1167490793222; Mon, 9 Oct 2017 16:17:55 -0700 (PDT) Received: from localhost ([::1]:60222 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e1hJ0-0006Mx-Ca for importer@patchew.org; Mon, 09 Oct 2017 19:17:50 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55418) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e1h0G-0006w5-Sw for qemu-devel@nongnu.org; Mon, 09 Oct 2017 18:58:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e1h0D-0005aJ-Qa for qemu-devel@nongnu.org; Mon, 09 Oct 2017 18:58:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50474) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1e1h0D-0005a5-K9 for qemu-devel@nongnu.org; Mon, 09 Oct 2017 18:58:25 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8A2C685363; Mon, 9 Oct 2017 22:58:24 +0000 (UTC) Received: from localhost (unknown [10.36.112.13]) by smtp.corp.redhat.com (Postfix) with ESMTP id C6E205ED4D; Mon, 9 Oct 2017 22:58:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 8A2C685363 Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=marcandre.lureau@redhat.com From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= To: qemu-devel@nongnu.org Date: Tue, 10 Oct 2017 00:56:15 +0200 Message-Id: <20171009225623.29232-35-marcandre.lureau@redhat.com> In-Reply-To: <20171009225623.29232-1-marcandre.lureau@redhat.com> References: <20171009225623.29232-1-marcandre.lureau@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 09 Oct 2017 22:58:24 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 34/42] tpm-passthrough: workaround a possible race X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , amarnath.valluri@intel.com, stefanb@linux.vnet.ibm.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Type: text/plain; charset="utf-8" The TPM backend processing thread has common shared variable race issues. (they should not be so easy to reach since guest interaction with the device is slow compared to host emulation) An obvious one is setting op_cancelled from device thread after calling write(cancel_fd). The backend thread may return before the device thread has set the variable. Instead set it before cancellation. Even if the write() failed, the end result is command get possibly cancelled (even if cancellation came from external sources it doesn't matter much). It's worth to consider removing the backend processing thread for now. Signed-off-by: Marc-Andr=C3=A9 Lureau Reviewed-by: Stefan Berger --- hw/tpm/tpm_passthrough.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/hw/tpm/tpm_passthrough.c b/hw/tpm/tpm_passthrough.c index 0806cf86af..d71d64e8aa 100644 --- a/hw/tpm/tpm_passthrough.c +++ b/hw/tpm/tpm_passthrough.c @@ -89,6 +89,7 @@ static int tpm_passthrough_unix_tx_bufs(TPMPassthruState = *tpm_pt, bool is_selftest; const struct tpm_resp_hdr *hdr; =20 + /* FIXME: protect shared variables or use other sync mechanism */ tpm_pt->tpm_op_canceled =3D false; tpm_pt->tpm_executing =3D true; *selftest_done =3D false; @@ -178,12 +179,11 @@ static void tpm_passthrough_cancel_cmd(TPMBackend *tb) */ if (tpm_pt->tpm_executing) { if (tpm_pt->cancel_fd >=3D 0) { + tpm_pt->tpm_op_canceled =3D true; n =3D write(tpm_pt->cancel_fd, "-", 1); if (n !=3D 1) { error_report("Canceling TPM command failed: %s", strerror(errno)); - } else { - tpm_pt->tpm_op_canceled =3D true; } } else { error_report("Cannot cancel TPM command due to missing " --=20 2.14.1.146.gd35faa819