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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 8715ACD4F21 for ; Sun, 17 May 2026 13:28:43 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BDB4C10E222; Sun, 17 May 2026 13:28:42 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=fail reason="signature verification failed" (2048-bit key; secure) header.d=berkoc.com header.i=@berkoc.com header.b="EoYmUfQ3"; dkim-atps=neutral Received: from mail-03.1984.is (mail-03.1984.is [93.95.224.70]) by gabe.freedesktop.org (Postfix) with ESMTPS id F371A10E222 for ; Sun, 17 May 2026 13:28:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=berkoc.com; s=1984; h=Content-Transfer-Encoding:Content-Type:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=PBjs0lncXBQIUANeQ0FdMkMsnlM+ULn4MUfrxqEcwrE=; b=EoYmUfQ3MeS4j3A1WqG8gqXVEv l+wOPiE6yg7icRPFywNqpc3i+6ozwTfquB6M/seo3tpuBWkRJJCGSSSsfPwGm/DbZ/svnqnB+c8H6 Zyayagx0/uaNyE85357t2QLWWS57AOZKeb9/Yhh7AO2GTLNhvAMbNUjmRapgepuVhltnySdxHrBY9 Du8lsN9IYdNGxtp7t0BOxmmT2wzDAla8taQoPtFoRUsH0SveqdgGhlnTrFICUPeHDuKBZU13Xmf/t inCqMt07/HluE4QOV53amG+wa+x+NJPjABi6TrtHEA4lMRCN/p3hoHDGLm6z1SCp6AR1XhmVrQIwf xkQzkb9A==; Received: from localhost by mail-03.1984.is with utf8esmtp (Exim 4.96) (envelope-from ) id 1wObGF-00H5VV-0s; Sun, 17 May 2026 13:10:28 +0000 From: Berkant Koc To: Saurabh Sengar , Dexuan Cui , Long Li Cc: linux-hyperv@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Wei Liu , Michael Kelley , Thomas Zimmermann , Maarten Lankhorst , Maxime Ripard , Deepak Rawat Subject: [PATCH 2/2] drm/hyperv: validate VMBus packet size in receive callback Date: Sun, 17 May 2026 14:55:02 +0200 Message-ID: <20260517-drm-hyperv-patch2@berkoc.com> In-Reply-To: <20260517-drm-hyperv-cover@berkoc.com> References: <20260517-drm-hyperv-cover@berkoc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Authenticated-User: me@berkoc.com X-Sender-Address: me@berkoc.com X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" hyperv_receive() reads bytes_recvd from vmbus_recvpacket() but does not forward that value to hyperv_receive_sub(). The sub-handler reads msg->vid_hdr.type and msg->feature_chg.is_dirt_needed without knowing how many bytes the host actually wrote, so a short packet leaves the parser reading bytes that the host did not write in this packet. The unconditional memcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE) on the wait-completion path also copies the full 16 KiB recv_buf regardless of bytes_recvd, including any residue from the prior message. Pass bytes_recvd into hyperv_receive_sub() and reject any packet shorter than the pipe + synthvid header. The dirt-feature branch additionally requires the feature_change payload size before reading is_dirt_needed. The init_buf copy now uses bytes_recvd as the length argument, which keeps it bounded by VMBUS_MAX_PACKET_SIZE through the new upper check. Fixes: 76c56a5affeb ("drm/hyperv: Add DRM driver for hyperv synthetic video device") Cc: stable@vger.kernel.org # 5.14+ Signed-off-by: Berkant Koc --- drivers/gpu/drm/hyperv/hyperv_drm_proto.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c index 003bb118d64c..0d32d9944c43 100644 --- a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c +++ b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c @@ -420,26 +420,35 @@ static int hyperv_get_supported_resolution(struct hv_device *hdev) return 0; } -static void hyperv_receive_sub(struct hv_device *hdev) +static void hyperv_receive_sub(struct hv_device *hdev, u32 bytes_recvd) { struct hyperv_drm_device *hv = hv_get_drvdata(hdev); struct synthvid_msg *msg; + size_t hdr_size; if (!hv) return; + hdr_size = sizeof(struct pipe_msg_hdr) + + sizeof(struct synthvid_msg_hdr); + if (bytes_recvd < hdr_size || bytes_recvd > VMBUS_MAX_PACKET_SIZE) + return; + msg = (struct synthvid_msg *)hv->recv_buf; /* Complete the wait event */ if (msg->vid_hdr.type == SYNTHVID_VERSION_RESPONSE || msg->vid_hdr.type == SYNTHVID_RESOLUTION_RESPONSE || msg->vid_hdr.type == SYNTHVID_VRAM_LOCATION_ACK) { - memcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE); + memcpy(hv->init_buf, msg, bytes_recvd); complete(&hv->wait); return; } if (msg->vid_hdr.type == SYNTHVID_FEATURE_CHANGE) { + if (bytes_recvd < hdr_size + + sizeof(struct synthvid_feature_change)) + return; hv->dirt_needed = msg->feature_chg.is_dirt_needed; if (hv->dirt_needed) hyperv_hide_hw_ptr(hv->hdev); @@ -466,7 +475,7 @@ static void hyperv_receive(void *ctx) &bytes_recvd, &req_id); if (bytes_recvd > 0 && recv_buf->pipe_hdr.type == PIPE_MSG_DATA) - hyperv_receive_sub(hdev); + hyperv_receive_sub(hdev, bytes_recvd); } while (bytes_recvd > 0 && ret == 0); } -- 2.47.3