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 B59FDC98311 for ; Thu, 24 Sep 2026 09:06:41 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x9fPB-0008Du-Gj; Thu, 24 Sep 2026 05:06:15 -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 1x9fP5-0008D9-SF for qemu-devel@nongnu.org; Thu, 24 Sep 2026 05:06:07 -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 1x9fP4-0000iT-4U for qemu-devel@nongnu.org; Thu, 24 Sep 2026 05:06:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1790240765; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RgjsTVF6YPcLBBYzsKri/GP8jiY61+tzms6P3IEX53Y=; b=TCU9O0QBN/opgjcIi977QfZLLd+SGfyhhDHqK9eYjrAGwLKZKtVMzjcK7OsRdUeyCv7CHe yHiG9NZC4Yey+1tl/FPFFjiuf/57Hy8dfZgN7W/7jTTHq1b5fABbLzw8N/e411/dvS2P8k Vj75tIeMsdOa4jFFomUNqRzWXOsEloA= Received: from mx-prod-mc-08.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-612-ReQXyg4hNVCw_4ZjGj1qBQ-1; Thu, 24 Sep 2026 05:06:03 -0400 X-MC-Unique: ReQXyg4hNVCw_4ZjGj1qBQ-1 X-Mimecast-MFC-AGG-ID: ReQXyg4hNVCw_4ZjGj1qBQ_1790240762 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 34EFC1883057; Thu, 24 Sep 2026 09:06:02 +0000 (UTC) Received: from thuth-p1g4.redhat.corp (headnet05.pony-001.prod.iad2.dc.redhat.com [10.2.32.117]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id F310C195604C; Thu, 24 Sep 2026 09:06:00 +0000 (UTC) From: Thomas Huth To: qemu-devel@nongnu.org, Richard Henderson Cc: XlabAI Team of Tencent Xuanwu Lab Subject: [PULL 1/7] hw/usb/hcd-xhci: Set reentrancy guard in timer functions (CVE-2026-17588) Date: Thu, 24 Sep 2026 11:05:52 +0200 Message-ID: <20260924090558.801845-2-thuth@redhat.com> In-Reply-To: <20260924090558.801845-1-thuth@redhat.com> References: <20260924090558.801845-1-thuth@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=thuth@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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-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: qemu development 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 The xHCI controller processes USB events from timer callbacks (xhci_mfwrap_timer and xhci_ep_kick_timer) outside of any MMIO handler context. The device's mem_reentrancy_guard is therefore not engaged during this processing. A malicious guest can exploit this by pointing the event ring base address (er_start) at the xHCI doorbell MMIO region. When xhci_write_event() performs a DMA write to deliver a transfer completion event, the write lands on doorbell register 0. If the written value is 0, this triggers xhci_process_commands() reentrantly. A CR_DISABLE_SLOT command prepared on the command ring then frees endpoint and transfer objects via xhci_disable_ep() / g_free() while the outer call stack still holds references to them, causing a heap use-after-free. Fix this by setting engaged_in_io on the device's mem_reentrancy_guard around the processing in these non-MMIO entry points. This mirrors the protection that EHCI, DWC2, and UHCI already have via qemu_bh_new_guarded(). With the guard active, the memory subsystem's automatic reentrancy check (system/memory.c) blocks DMA writes that would dispatch into the device's own MMIO handlers. CVE: CVE-2026-17588 Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3926 Reported-by: XlabAI Team of Tencent Xuanwu Lab , Guannan Wang , Zhanpeng Liu , Jiashuo Liang <761232680@qq.com>, Guancheng Li Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/4195 Reported By: Ken Hsu and Royce Lu of Palo Alto Networks Message-ID: <20260915112213.525283-1-thuth@redhat.com> Signed-off-by: Thomas Huth --- hw/usb/hcd-xhci.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c index d342aa2739e..12f8ffece0f 100644 --- a/hw/usb/hcd-xhci.c +++ b/hw/usb/hcd-xhci.c @@ -456,9 +456,15 @@ static void xhci_mfwrap_timer(void *opaque) { XHCIState *xhci = opaque; XHCIEvent wrap = { ER_MFINDEX_WRAP, CC_SUCCESS }; + MemReentrancyGuard *guard = &xhci->parent.mem_reentrancy_guard; + + assert(!guard->engaged_in_io); + guard->engaged_in_io = true; xhci_event(xhci, &wrap, 0); xhci_mfwrap_update(xhci); + + guard->engaged_in_io = false; } static void xhci_die(XHCIState *xhci) @@ -1086,7 +1092,14 @@ static void xhci_set_ep_state(XHCIState *xhci, XHCIEPContext *epctx, static void xhci_ep_kick_timer(void *opaque) { XHCIEPContext *epctx = opaque; + MemReentrancyGuard *guard = &epctx->xhci->parent.mem_reentrancy_guard; + + assert(!guard->engaged_in_io); + guard->engaged_in_io = true; + xhci_kick_epctx(epctx, 0); + + guard->engaged_in_io = false; } static XHCIEPContext *xhci_alloc_epctx(XHCIState *xhci, -- 2.55.0