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 lists1p.gnu.org (lists1p.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 6BA82C43458 for ; Mon, 13 Jul 2026 16:05:33 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wjJ9f-0004aF-6p; Mon, 13 Jul 2026 12:05:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wjJ9c-0004VD-Od for qemu-trivial@nongnu.org; Mon, 13 Jul 2026 12:05:12 -0400 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 1wjJ9b-0005q8-An for qemu-trivial@nongnu.org; Mon, 13 Jul 2026 12:05:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783958710; 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; bh=IPwmvNgzpvqEs2n7dYPiWnQDbwjka8OPTrkMOq5/BEY=; b=PkVcQZ90Fpzouy490NXGEtza8F+d5hkAccfj167TitOqDmYfkhdPuEILG3meKwtr3ib9wM q3OHzyGbb6WnBDgzuWl2H4Qvq9ymdCnP1g8t4eETEhZLwCUxV3CYAXvruQ2SstdsurxWxm HIk/tTIuoxDs3Gcj5bKivsIxvxIyKjU= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-682-aZgzCPb5NMKcvswGzF-Flw-1; Mon, 13 Jul 2026 12:05:05 -0400 X-MC-Unique: aZgzCPb5NMKcvswGzF-Flw-1 X-Mimecast-MFC-AGG-ID: aZgzCPb5NMKcvswGzF-Flw_1783958704 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DC6E21955DDE; Mon, 13 Jul 2026 16:05:03 +0000 (UTC) Received: from thuth-p1g4.redhat.com (unknown [10.44.48.15]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 7CB2B3000B52; Mon, 13 Jul 2026 16:04:59 +0000 (UTC) From: Thomas Huth To: qemu-devel@nongnu.org Cc: qemu-trivial@nongnu.org, Peter Maydell , Munkhbaatar Enkhbaatar , =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , qemu-stable@nongnu.org Subject: [PATCH] hw/usb/hcd-ohci: Make sure that ohci_service_ed_list() cannot loop forever Date: Mon, 13 Jul 2026 18:04:58 +0200 Message-ID: <20260713160458.343323-1-thuth@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: 4SyevlMQ9Lbn8pI3dzE3EJzC1uNHE7EnMPbuRlTqrEE_1783958704 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Received-SPF: permerror client-ip=170.10.133.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, T_SPF_PERMERROR=0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-trivial@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-trivial-bounces+qemu-trivial=archiver.kernel.org@nongnu.org Sender: qemu-trivial-bounces+qemu-trivial=archiver.kernel.org@nongnu.org From: Thomas Huth The inner while loop in ohci_service_ed_list() could theoretically loop forever if a malicious guest prepares a set of bad descriptors. Add a check to the loop to avoid this situation. Reported-by: Feifan Qian Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3781 Signed-off-by: Thomas Huth --- hw/usb/hcd-ohci.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c index 40ebafb4dd9..c4a9741bd42 100644 --- a/hw/usb/hcd-ohci.c +++ b/hw/usb/hcd-ohci.c @@ -28,6 +28,7 @@ #include "qemu/osdep.h" #include "hw/core/irq.h" #include "qapi/error.h" +#include "qemu/log.h" #include "qemu/module.h" #include "qemu/timer.h" #include "hw/usb/usb.h" @@ -1129,6 +1130,8 @@ static int ohci_service_ed_list(OHCIState *ohci, uint32_t head) return 0; } for (cur = head; cur && link_cnt++ < ED_LINK_LIMIT; cur = next_ed) { + unsigned int ed_cnt = 0; + if (ohci_read_ed(ohci, cur, &ed)) { trace_usb_ohci_ed_read_error(cur); ohci_die(ohci); @@ -1172,6 +1175,13 @@ static int ohci_service_ed_list(OHCIState *ohci, uint32_t head) break; } } + + if (ed_cnt++ > ED_LINK_LIMIT) { + qemu_log_mask(LOG_GUEST_ERROR, + "ohci: Too many endpoint descriptors in loop\n"); + ohci_die(ohci); + return 0; + } } if (ohci_put_ed(ohci, cur, &ed)) { -- 2.55.0