From nobody Sat Jul 25 21:23:34 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1783947136; cv=none; d=zohomail.com; s=zohoarc; b=etU6VY86eDIQmkvFDc2Kp76wmWTypPsPFGYQf0FPqIzZepv89mTcjoEcvLrbg5vYsiBk45oyao/wqzv7kJol4Vdo3V3TJHouUiHtcXLVF4XiNJ84yNPyMwyCabs9AnVqO92F6E1RkUcWFhImFCYu4PvZQhdoJ1R3u3axnxj0tNM= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1783947136; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=xBCRhKksK85VC4gIzUEZycAGMGy0x9PL2hAUdX3iQeM=; b=WMjF68i7YBusZUhvW1zkbnqRMkL1GPFrXl/DCKDfE9dxHgD9RZs4kEsqhhr3RXjdWCkBIPVnFKEyYVo9S74keDbVRNLth5ddTY1Smc46xyG1zoe0nXaLH+uOsrE06IOLeb06UALmn4sQC3SGJg+QbjmBOhP1sweyidSeIM5f4VE= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1783947136634242.79145741814955; Mon, 13 Jul 2026 05:52:16 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wjG8P-00046d-JW; Mon, 13 Jul 2026 08:51:45 -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 1wjG8M-00046P-3W for qemu-devel@nongnu.org; Mon, 13 Jul 2026 08:51:42 -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 1wjG8K-0005mR-89 for qemu-devel@nongnu.org; Mon, 13 Jul 2026 08:51:41 -0400 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-508-YFtPgcdUMSy1AtU948EdFQ-1; Mon, 13 Jul 2026 08:51:36 -0400 Received: from mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.95]) (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 E44D51955D5E for ; Mon, 13 Jul 2026 12:51:35 +0000 (UTC) Received: from localhost (unknown [10.44.22.3]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 5735936F29; Mon, 13 Jul 2026 12:51:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783947099; 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=xBCRhKksK85VC4gIzUEZycAGMGy0x9PL2hAUdX3iQeM=; b=Df7G0gSv5pbjYlOY8FJEvYX2TIhwNaKJa1SRLVh7CyNmElU9Kt58jOZaEBUtW4Yj5xwQul IyZgpsaSNdJq+Vk+lJrbBAJKUjb/lrCOfBiL1Gz76uxl7Te16p/P0xP5wWsEWbZVZbwme+ v8gyygIKttalehX83WT9krWcesRktKU= X-MC-Unique: YFtPgcdUMSy1AtU948EdFQ-1 X-Mimecast-MFC-AGG-ID: YFtPgcdUMSy1AtU948EdFQ_1783947096 From: marcandre.lureau@redhat.com To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , "Michael S. Tsirkin" , Stefano Garzarella Subject: [PATCH] hw/display/vhost-user-gpu: validate message payload sizes Date: Mon, 13 Jul 2026 16:51:30 +0400 Message-ID: <20260713125130.101787-1-marcandre.lureau@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: permerror client-ip=170.10.133.124; envelope-from=marcandre.lureau@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-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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1783947138663158500 From: Marc-Andr=C3=A9 Lureau A malicious or buggy vhost-user-gpu backend can send messages with undersized payloads, leading to out-of-bounds reads when the handler accesses struct fields beyond the allocated buffer. However, vhost-user-gpu is considered trusted by QEMU by design (it has access to shared memory etc). Add a centralized minimum payload size check in vhost_user_gpu_chr_read() that rejects messages before dispatch, and a per-pixel bounds check in the VHOST_USER_GPU_UPDATE handler to ensure the variable-length data covers the declared width x height. Fixes: 267f66465 ("hw/display: add vhost-user-vga & gpu-pci") Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3866 Reported-by: Feifan Qian Signed-off-by: Marc-Andr=C3=A9 Lureau Reviewed-by: Thomas Huth --- hw/display/vhost-user-gpu.c | 38 +++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/hw/display/vhost-user-gpu.c b/hw/display/vhost-user-gpu.c index 57360898ca0..cd684d63639 100644 --- a/hw/display/vhost-user-gpu.c +++ b/hw/display/vhost-user-gpu.c @@ -119,6 +119,31 @@ static VhostUserGpuMsg m __attribute__ ((unused)); =20 static void vhost_user_gpu_update_blocked(VhostUserGPU *g, bool blocked); =20 +static size_t +vhost_user_gpu_min_payload_size(VhostUserGpuRequest request) +{ + switch (request) { + case VHOST_USER_GPU_CURSOR_POS: + case VHOST_USER_GPU_CURSOR_POS_HIDE: + return sizeof(VhostUserGpuCursorPos); + case VHOST_USER_GPU_CURSOR_UPDATE: + return sizeof(VhostUserGpuCursorUpdate); + case VHOST_USER_GPU_GET_EDID: + return sizeof(VhostUserGpuEdidRequest); + case VHOST_USER_GPU_SCANOUT: + return sizeof(VhostUserGpuScanout); + case VHOST_USER_GPU_DMABUF_SCANOUT: + return sizeof(VhostUserGpuDMABUFScanout); + case VHOST_USER_GPU_DMABUF_SCANOUT2: + return sizeof(VhostUserGpuDMABUFScanout2); + case VHOST_USER_GPU_DMABUF_UPDATE: + case VHOST_USER_GPU_UPDATE: + return sizeof(VhostUserGpuUpdate); + default: + return 0; + } +} + static void vhost_user_gpu_handle_cursor(VhostUserGPU *g, VhostUserGpuMsg *msg) { @@ -322,6 +347,14 @@ vhost_user_gpu_handle_display(VhostUserGPU *g, VhostUs= erGpuMsg *msg) if (m->scanout_id >=3D g->parent_obj.conf.max_outputs) { break; } + + if ((uint64_t)m->width * m->height > + (msg->size - sizeof(VhostUserGpuUpdate)) / sizeof(uint32_t)) { + error_report("vhost-user-gpu: update payload too small" + " for %ux%u", m->width, m->height); + break; + } + s =3D &g->parent_obj.scanout[m->scanout_id]; con =3D s->con; pixman_image_t *image =3D @@ -396,6 +429,11 @@ vhost_user_gpu_chr_read(void *opaque) msg->flags =3D flags; msg->size =3D size; =20 + if (size < vhost_user_gpu_min_payload_size(request)) { + error_report("vhost-user-gpu: message %d payload too small", reque= st); + goto end; + } + if (request =3D=3D VHOST_USER_GPU_CURSOR_UPDATE || request =3D=3D VHOST_USER_GPU_CURSOR_POS || request =3D=3D VHOST_USER_GPU_CURSOR_POS_HIDE) { --=20 2.55.0