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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3F7EEC28B2E for ; Wed, 12 Mar 2025 08:40:41 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tsHd5-000612-RY; Wed, 12 Mar 2025 04:39:55 -0400 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 1tsHd4-00060c-96 for qemu-devel@nongnu.org; Wed, 12 Mar 2025 04:39:54 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tsHd2-0007h5-PX for qemu-devel@nongnu.org; Wed, 12 Mar 2025 04:39:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741768790; 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; bh=yLmnimSeJ1QTguOn2Vc00jlRK6+YVxNyJ1zqKwWKr3c=; b=OnzvnQz/nzaSHwKvEHtUQhhzrCUFBUWJpuOTJEsI9OC6Cgqdngt2e6lTcu0hndSbAzDwZZ 9zhYZTspBZnwywLv7Luyc4WbO5YR2sj+DViXdyyLSBOlJ8ZEW0EVdeXzyY/HXWF82znLLQ 8hQWWzs/QP9y3X523KqEeQ+/EEccdak= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-29-FLSn8D7fNM2Hx-jf25MGPA-1; Wed, 12 Mar 2025 04:39:46 -0400 X-MC-Unique: FLSn8D7fNM2Hx-jf25MGPA-1 X-Mimecast-MFC-AGG-ID: FLSn8D7fNM2Hx-jf25MGPA_1741768785 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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 mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8F7A9180025B; Wed, 12 Mar 2025 08:39:45 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.22.74.4]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 933581956095; Wed, 12 Mar 2025 08:39:44 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 6E51421E675E; Wed, 12 Mar 2025 09:39:40 +0100 (CET) From: Markus Armbruster To: qemu-devel@nongnu.org Cc: Bibo Mao , Song Gao Subject: Bad error handling in loongarch's kvm_arch_init_vcpu(), need advice Date: Wed, 12 Mar 2025 09:39:40 +0100 Message-ID: <87wmcumylv.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org scripts/coccinelle/error-use-after-free.cocci led me to target/loongarch/kvm/kvm.c: int kvm_arch_init_vcpu(CPUState *cs) { uint64_t val; int ret; Error *local_err = NULL; ret = 0; qemu_add_vm_change_state_handler(kvm_loongarch_vm_stage_change, cs); if (!kvm_get_one_reg(cs, KVM_REG_LOONGARCH_DEBUG_INST, &val)) { brk_insn = val; } ret = kvm_cpu_check_lsx(cs, &local_err); if (ret < 0) { error_report_err(local_err); Reporting an error, but continue anyway. This is suspicious. Note for later: @local_error is now non-null. } ret = kvm_cpu_check_lasx(cs, &local_err); Passing non-null @local_error to kvm_cpu_check_lasx(). This is wrong. When kvm_cpu_check_lasx() fails and passes &local_error to error_setg(), error_setv()'s assertion will fail. Two possible fixes: 1. If continuing after kvm_cpu_check_lasx() failure is correct, we need to clear @local_error there. Since it's not actually an error then, we should almost certainly not use error_report_err() there. *Maybe* warn_report_err(). 2. If continuing is wrong, we probably need to return ret. What is the correct fix? if (ret < 0) { error_report_err(local_err); Likewise. } ret = kvm_cpu_check_lbt(cs, &local_err); if (ret < 0) { error_report_err(local_err); Likewise. } ret = kvm_cpu_check_pmu(cs, &local_err); if (ret < 0) { error_report_err(local_err); Likewise. } ret = kvm_cpu_check_pv_features(cs, &local_err); if (ret < 0) { error_report_err(local_err); Best to do the same here. } return ret; }