From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 734A313B78F; Tue, 27 Feb 2024 13:46:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709041591; cv=none; b=YxJpndP90yFCG1zraVLfg7SwGts4Mw0PieyXngD+Wtjn2TV0//k94FZ7dF9xnnRQsst3u7HZJbJr6lr07ClMXZSUpxBqUGqzKI6+cv9UgqVz2r4FTxBTAAm3iUPsgEBlA1+yzOrGuaDIWeSqI8iZL6uQTtiHTyaBSe6gylErL/M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709041591; c=relaxed/simple; bh=VRQpZvELbvFAP77PUSphEXFOjcuBAOLTqqdzCvMkl4w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=UBjbGyCI4FO0X9Oby/g+WJyG8lE77rPstF+XoR+/P4SZz+4068w5gJkRtERbzNPivPnc7wp1iUoQB/DroCgWqImjNvrJi8wylALGCpTvvOd/MyuIjRDRaRI77EBNODNX2MPuSLEnYW5P0N7nv3Rdqy+0esAjGR6+KKKDap4ROU0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=svA21sZC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="svA21sZC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04C50C433C7; Tue, 27 Feb 2024 13:46:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1709041591; bh=VRQpZvELbvFAP77PUSphEXFOjcuBAOLTqqdzCvMkl4w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=svA21sZCxQM2yU3Y46Kk3MncuUjtWZQVydn6D0l+YXGHgPlH61cq1Q2n66oR8/Bls 2I1z9kt5HVzUmtk3+lES7j+X95ruzmgSA2PXSy1zWEZ/irkXa6q90ocP416M0EEWv0 ei9Jh5LIT7arUseOmWYCYxnwIdoHA7a7JnwHtzSQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Krishna Kurapati , =?UTF-8?q?Maciej=20=C5=BBenczykowski?= Subject: [PATCH 4.19 33/52] usb: gadget: ncm: Avoid dropping datagrams of properly parsed NTBs Date: Tue, 27 Feb 2024 14:26:20 +0100 Message-ID: <20240227131549.620852538@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240227131548.514622258@linuxfoundation.org> References: <20240227131548.514622258@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Krishna Kurapati commit 76c51146820c5dac629f21deafab0a7039bc3ccd upstream. 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 Reviewed-by: Maciej Żenczykowski Link: https://lore.kernel.org/r/20240205074650.200304-1-quic_kriskura@quicinc.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_ncm.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -1349,7 +1349,15 @@ parse_ntb: "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; }