Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964871AbcCKIoq (ORCPT ); Fri, 11 Mar 2016 03:44:46 -0500 Received: from smtprelay01.ispgateway.de ([80.67.31.35]:34566 "EHLO smtprelay01.ispgateway.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935218AbcCKIoh (ORCPT ); Fri, 11 Mar 2016 03:44:37 -0500 Subject: Re: [PATCH] usb: gadget: f_midi: Fixed a bug when buflen was smaller than wMaxPacketSize To: Steve Calfee , "Felipe F. Tonello" References: <1457552370-29404-1-git-send-email-eu@felipetonello.com> Cc: USB list , Kernel development list , Felipe Balbi , Michal Nazarewicz , Robert Baldyga From: Clemens Ladisch Message-ID: <56E2856E.2070306@ladisch.de> Date: Fri, 11 Mar 2016 09:44:30 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Df-Sender: bGludXgtdXNiQGNsLmRvbWFpbmZhY3Rvcnkta3VuZGUuZGU= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 916 Lines: 22 Steve Calfee wrote: > On Wed, Mar 9, 2016 at 11:39 AM, Felipe F. Tonello wrote: >> [...] >> This patch fixes this problem by setting the minimum usb_request's buffer size >> for the OUT endpoint as its wMaxPacketSize. >> >> --- a/drivers/usb/gadget/function/f_midi.c >> +++ b/drivers/usb/gadget/function/f_midi.c >> @@ -366,7 +366,9 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt) >> struct usb_request *req = >> - midi_alloc_ep_req(midi->out_ep, midi->buflen); >> + midi_alloc_ep_req(midi->out_ep, >> + max_t(unsigned, midi->buflen, >> + bulk_out_desc.wMaxPacketSize)); > > Won't you get a buffer overrun if midi->buflen is less than wMaxPacketSize? No. f_midi_handle_out_data() uses only the request buffer. Regards, Clemens