From patchwork Mon Feb 5 07:46:50 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Krishna Kurapati X-Patchwork-Id: 770324 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B4E9D11190; Mon, 5 Feb 2024 07:47:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707119253; cv=none; b=b9yJ6CzRjkVDgT5Qhbhd07hMhwfhgFR/8njLCp4QytciFirbbmBOt5dwtcROCuO1aexuEh28cRqCGraDG53L4+NI+fxIJ3yWKeYZ8DJ5pVfWIs5nPrDLCXOag1BsXmujnS70DsnZZulwVn26h3rv1DYJg9ABFCGxFPo4PVZFKfk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707119253; c=relaxed/simple; bh=gvdIDaltTS0ihBKlSJXlAE64b+5OpymAOgP9TR84kks=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=pNnxujajShlwZHUzLNMDHwxKmfMM5ZAbS+jgx1H6m1d2cmup9zp5SqALs7uaEGRUNJDESKF9c9EEJrCVwU6A3haL7jeq5NX8PUZG+inW85U68wCq07+LugQqo26w0zfh356W9X7J7lhPnRPN+pLSaBoahabdn0h6BrNJ5TC0Z9c= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com; spf=pass smtp.mailfrom=quicinc.com; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b=Rq/K7jZl; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=quicinc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b="Rq/K7jZl" Received: from pps.filterd (m0279862.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.24/8.17.1.24) with ESMTP id 4154xFFo003831; Mon, 5 Feb 2024 07:47:20 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h= from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding:content-type; s=qcppdkim1; bh=H43mdPT LvVJVPRl+DPOkCMfp+JmkCA5TA8E3ZocTvR4=; b=Rq/K7jZl97cLFk5SHgDRy6A 2CbFshNw5hthllYCRL+1iRS0LwNeliX4IiSJ8d3uypwGVVu+CIou+89QbgrOnz+q K6lmF/Q32AMst5o35Ts3DX2TLHzcO94jWxZscljeNWZCv24qlC6yzgdyB8ezqHNS K9/08w8/jr5GIaoacq6kAhf6uvF2AbYXY4yXvoj41fJQeEHaYkV6Xt0CuLK7AJXH JPnDGf2W3Wqj3obsXH6WDvPAYvLrW0tSm4sAUhIePBZBqH5xpQ+8yg61c+jwaxyY 2Jd7gsVRrg3mJxKjXPyg7CWFR/zaeEr4ocn0n8q3w90XuIOIpch7C+iOXxE/hGA= = Received: from nasanppmta03.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3w2rvj89m4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 05 Feb 2024 07:47:20 +0000 (GMT) Received: from nasanex01c.na.qualcomm.com (nasanex01c.na.qualcomm.com [10.45.79.139]) by NASANPPMTA03.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 4157l5YL002700 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 5 Feb 2024 07:47:05 GMT Received: from hu-kriskura-hyd.qualcomm.com (10.80.80.8) by nasanex01c.na.qualcomm.com (10.45.79.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Sun, 4 Feb 2024 23:47:02 -0800 From: Krishna Kurapati To: Greg Kroah-Hartman , =?utf-8?q?Maciej_=C5=BB?= =?utf-8?q?enczykowski?= , Hardik Gajjar CC: , , , , , Krishna Kurapati , Subject: [PATCH v3] usb: gadget: ncm: Avoid dropping datagrams of properly parsed NTBs Date: Mon, 5 Feb 2024 13:16:50 +0530 Message-ID: <20240205074650.200304-1-quic_kriskura@quicinc.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nasanex01c.na.qualcomm.com (10.45.79.139) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: 4-tTLD6_E1V8ZOQTbSjRVm22jzLoejB1 X-Proofpoint-GUID: 4-tTLD6_E1V8ZOQTbSjRVm22jzLoejB1 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-02-05_03,2024-01-31_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 adultscore=0 phishscore=0 mlxlogscore=485 bulkscore=0 mlxscore=0 clxscore=1011 suspectscore=0 spamscore=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2401310000 definitions=main-2402050059 It is observed sometimes when tethering is used over NCM with Windows 11 as host, at some instances, the gadget_giveback has one byte appended at the end of a proper NTB. When the NTB is parsed, unwrap call looks for any leftover bytes in SKB provided by u_ether and if there are any pending bytes, it treats them as a separate NTB and parses it. But in case the second NTB (as per unwrap call) is faulty/corrupt, all the datagrams that were parsed properly in the first NTB and saved in rx_list are dropped. Adding a few custom traces showed the following: [002] d..1 7828.532866: dwc3_gadget_giveback: ep1out: req 000000003868811a length 1025/16384 zsI ==> 0 [002] d..1 7828.532867: ncm_unwrap_ntb: K: ncm_unwrap_ntb toprocess: 1025 [002] d..1 7828.532867: ncm_unwrap_ntb: K: ncm_unwrap_ntb nth: 1751999342 [002] d..1 7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb seq: 0xce67 [002] d..1 7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb blk_len: 0x400 [002] d..1 7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb ndp_len: 0x10 [002] d..1 7828.532869: ncm_unwrap_ntb: K: Parsed NTB with 1 frames In this case, the giveback is of 1025 bytes and block length is 1024. The rest 1 byte (which is 0x00) won't be parsed resulting in drop of all datagrams in rx_list. Same is case with packets of size 2048: [002] d..1 7828.557948: dwc3_gadget_giveback: ep1out: req 0000000011dfd96e length 2049/16384 zsI ==> 0 [002] d..1 7828.557949: ncm_unwrap_ntb: K: ncm_unwrap_ntb nth: 1751999342 [002] d..1 7828.557950: ncm_unwrap_ntb: K: ncm_unwrap_ntb blk_len: 0x800 Lecroy shows one byte coming in extra confirming that the byte is coming in from PC: Transfer 2959 - Bytes Transferred(1025) Timestamp((18.524 843 590) - Transaction 8391 - Data(1025 bytes) Timestamp(18.524 843 590) --- Packet 4063861 Data(1024 bytes) Duration(2.117us) Idle(14.700ns) Timestamp(18.524 843 590) --- Packet 4063863 Data(1 byte) Duration(66.160ns) Time(282.000ns) Timestamp(18.524 845 722) According to Windows driver, no ZLP is needed if wBlockLength is non-zero, because the non-zero wBlockLength has already told the function side the size of transfer to be expected. However, there are in-market NCM devices that rely on ZLP as long as the wBlockLength is multiple of wMaxPacketSize. To deal with such devices, it pads an extra 0 at end so the transfer is no longer multiple of wMaxPacketSize. Cc: Fixes: 9f6ce4240a2b ("usb: gadget: f_ncm.c added") Signed-off-by: Krishna Kurapati --- Link to v2: https://lore.kernel.org/all/20240131150332.1326523-1-quic_kriskura@quicinc.com/ Changes in v2: Added check to see if the padded byte is 0x00. Changes in v3: Removed wMaxPacketSize check from v2. drivers/usb/gadget/function/f_ncm.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c index ca5d5f564998..e2a059cfda2c 100644 --- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -1338,7 +1338,15 @@ static int ncm_unwrap_ntb(struct gether *port, "Parsed NTB with %d frames\n", dgram_counter); to_process -= block_len; - if (to_process != 0) { + + /* + * Windows NCM driver avoids USB ZLPs by adding a 1-byte + * zero pad as needed. + */ + if (to_process == 1 && + (*(unsigned char *)(ntb_ptr + block_len) == 0x00)) { + to_process--; + } else if (to_process > 0) { ntb_ptr = (unsigned char *)(ntb_ptr + block_len); goto parse_ntb; }