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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0AC3FC43603 for ; Tue, 17 Dec 2019 00:56:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB2A224673 for ; Tue, 17 Dec 2019 00:56:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727458AbfLQA4m (ORCPT ); Mon, 16 Dec 2019 19:56:42 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35082 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726933AbfLQAvl (ORCPT ); Mon, 16 Dec 2019 19:51:41 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1ih15K-0003M9-8M; Tue, 17 Dec 2019 00:51:34 +0000 Received: from ben by deadeye with local (Exim 4.93-RC7) (envelope-from ) id 1ih15J-0005bG-P9; Tue, 17 Dec 2019 00:51:33 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Alan Stern" , "Felipe Balbi" , "Greg Kroah-Hartman" Date: Tue, 17 Dec 2019 00:47:16 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 102/136] USB: gadget: Reject endpoints with 0 maxpacket value In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.80-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern commit 54f83b8c8ea9b22082a496deadf90447a326954e upstream. Endpoints with a maxpacket length of 0 are probably useless. They can't transfer any data, and it's not at all unlikely that a UDC will crash or hang when trying to handle a non-zero-length usb_request for such an endpoint. Indeed, dummy-hcd gets a divide error when trying to calculate the remainder of a transfer length by the maxpacket value, as discovered by the syzbot fuzzer. Currently the gadget core does not check for endpoints having a maxpacket value of 0. This patch adds a check to usb_ep_enable(), preventing such endpoints from being used. As far as I know, none of the gadget drivers in the kernel tries to create an endpoint with maxpacket = 0, but until now there has been nothing to prevent userspace programs under gadgetfs or configfs from doing it. Signed-off-by: Alan Stern Reported-and-tested-by: syzbot+8ab8bf161038a8768553@syzkaller.appspotmail.com Acked-by: Felipe Balbi Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.1910281052370.1485-100000@iolanthe.rowland.org Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- include/linux/usb/gadget.h | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/include/linux/usb/gadget.h +++ b/include/linux/usb/gadget.h @@ -222,6 +222,16 @@ static inline void usb_ep_set_maxpacket_ */ static inline int usb_ep_enable(struct usb_ep *ep) { + /* UDC drivers can't handle endpoints with maxpacket size 0 */ + if (usb_endpoint_maxp(ep->desc) == 0) { + /* + * We should log an error message here, but we can't call + * dev_err() because there's no way to find the gadget + * given only ep. + */ + return -EINVAL; + } + return ep->ops->enable(ep, ep->desc); }