From patchwork Mon Mar 4 14:44:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= X-Patchwork-Id: 1907650 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=CGaNDI4m; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=patchwork.ozlabs.org) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4TpM2S59ngz23qX for ; Tue, 5 Mar 2024 01:46:08 +1100 (AEDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rh9ZD-0007B5-Ep; Mon, 04 Mar 2024 09:45:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rh9Z0-00078E-0X for qemu-devel@nongnu.org; Mon, 04 Mar 2024 09:45:12 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rh9Yx-0006MI-FG for qemu-devel@nongnu.org; Mon, 04 Mar 2024 09:45:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709563506; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CLvvnawf8Y0JAJgS0FG+ATI5m0ZuxaniOd3uQ0mOM8A=; b=CGaNDI4m18auHMlMhJhN33JNRcn23b8SQpa7TaVQisIi10DtlbMnpcZ3VqJjSXWL9s/uQH E753OlxLCQ3u67Thlgb5GnYqOMFt91XazsRbDfEP78N7BDZiLn9SwJKl3Z2K8xoTdnejRa SRFCWja5COEzD06wTGX2cxDEtDEjBsI= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-156-9TdeOOI2OkWutwADUWbgIw-1; Mon, 04 Mar 2024 09:45:01 -0500 X-MC-Unique: 9TdeOOI2OkWutwADUWbgIw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 89150891F20; Mon, 4 Mar 2024 14:45:01 +0000 (UTC) Received: from toolbox.redhat.com (unknown [10.42.28.54]) by smtp.corp.redhat.com (Postfix) with ESMTP id DEC882166B35; Mon, 4 Mar 2024 14:44:59 +0000 (UTC) From: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: Wainer dos Santos Moschetta , Thomas Huth , Beraldo Leal , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Paolo Bonzini , =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , =?utf-8?q?Alex_Benn=C3=A9e?= , =?utf-8?q?Daniel_P?= =?utf-8?q?=2E_Berrang=C3=A9?= Subject: [PATCH 1/2] meson: detect broken clang 17 with -fzero-call-used-regs Date: Mon, 4 Mar 2024 14:44:55 +0000 Message-ID: <20240304144456.3825935-2-berrange@redhat.com> In-Reply-To: <20240304144456.3825935-1-berrange@redhat.com> References: <20240304144456.3825935-1-berrange@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.571, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Clang 17 will segv if given -fzero-call-used-regs and optimization is enabled. Since upstream hasn't triaged the bug, distros are increasingly shipping with broken Clang. https://github.com/llvm/llvm-project/issues/75168 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277474 Signed-off-by: Daniel P. Berrangé Reviewed-by: Peter Maydell --- meson.build | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/meson.build b/meson.build index 0ef1654e86..762798f2ee 100644 --- a/meson.build +++ b/meson.build @@ -555,17 +555,24 @@ endif # Check further flags that make QEMU more robust against malicious parties hardening_flags = [ - # Zero out registers used during a function call - # upon its return. This makes it harder to assemble - # ROP gadgets into something usable - '-fzero-call-used-regs=used-gpr', - # Initialize all stack variables to zero. This makes # it harder to take advantage of uninitialized stack # data to drive exploits '-ftrivial-auto-var-init=zero', ] +# Zero out registers used during a function call +# upon its return. This makes it harder to assemble +# ROP gadgets into something usable +# +# NB: CLang 17 is broken and SEGVs +# https://github.com/llvm/llvm-project/issues/75168 +if cc.compiles('extern struct { void (*cb)(void); } s; void f(void) { s.cb(); }', + name: '-fzero-call-used-regs=used-gpr', + args: ['-O2', '-fzero-call-used-regs=used-gpr']) + hardening_flags += '-fzero-call-used-regs=used-gpr' +endif + qemu_common_flags += cc.get_supported_arguments(hardening_flags) add_global_arguments(qemu_common_flags, native: false, language: all_languages)