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=-11.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 15690C4363A for ; Thu, 29 Oct 2020 01:13:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B94C520731 for ; Thu, 29 Oct 2020 01:13:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="r4eejURJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391188AbgJ2BN6 (ORCPT ); Wed, 28 Oct 2020 21:13:58 -0400 Received: from z5.mailgun.us ([104.130.96.5]:29878 "EHLO z5.mailgun.us" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730281AbgJ2BN5 (ORCPT ); Wed, 28 Oct 2020 21:13:57 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1603934036; h=In-Reply-To: Content-Type: MIME-Version: References: Message-ID: Subject: Cc: To: From: Date: Sender; bh=3v5giW8N63c8Nh4IYAiZJNSwUxB/hCxFjqckHHRRmrg=; b=r4eejURJB4/pXYFqhgGFz6c9WP9bb6A1GToANuV3UFjAPI2kVoPYxGtNpWUsbrMNTV7LbyJo pvrfts9A1mKglBXtTuReC5GPpvybudhPcKurMIWKCZ2OHcOkDzXEdF2IhViFSPI9kPiixHQW 4hW+g4qjsWCkvhW1uZfixnUZPIs= X-Mailgun-Sending-Ip: 104.130.96.5 X-Mailgun-Sid: WyIxZTE2YSIsICJsaW51eC11c2JAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n06.prod.us-east-1.postgun.com with SMTP id 5f99a7d3ff9aaeadc925bc0e (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 28 Oct 2020 17:18:11 GMT Sender: jackp=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 07765C43382; Wed, 28 Oct 2020 17:18:11 +0000 (UTC) Received: from jackp-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: jackp) by smtp.codeaurora.org (Postfix) with ESMTPSA id C6088C433F0; Wed, 28 Oct 2020 17:18:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org C6088C433F0 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=jackp@codeaurora.org Date: Wed, 28 Oct 2020 10:17:51 -0700 From: Jack Pham To: Peter Chen Cc: Felipe Balbi , Ruslan Bilovol , Greg Kroah-Hartman , Thinh Nguyen , Andy Shevchenko , "linux-usb@vger.kernel.org" , Ferry Toth Subject: Re: [PATCH] usb: gadget: audio: Free requests only after callback Message-ID: <20201028171738.GA1620@jackp-linux.qualcomm.com> References: <20201027233138.13712-1-jackp@codeaurora.org> <20201028071503.GA21171@b29397-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201028071503.GA21171@b29397-desktop> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Hi Peter, On Wed, Oct 28, 2020 at 07:15:31AM +0000, Peter Chen wrote: > On 20-10-27 16:31:38, Jack Pham wrote: > > As per the kernel doc for usb_ep_dequeue(), it states that "this > > routine is asynchronous, that is, it may return before the completion > > routine runs". And indeed since v5.0 the dwc3 gadget driver updated > > its behavior to place dequeued requests on to a cancelled list to be > > given back later after the endpoint is stopped. > > > > The free_ep() was incorrectly assuming that a request was ready to > > be freed after calling dequeue which results in a use-after-free > > in dwc3 when it traverses its cancelled list. Fix this by moving > > the usb_ep_free_request() call to the callback itself in case the > > ep is disabled. > > > > Fixes: eb9fecb9e69b0 ("usb: gadget: f_uac2: split out audio core") > > Reported-and-tested-by: Ferry Toth > > Signed-off-by: Jack Pham > > --- > > drivers/usb/gadget/function/u_audio.c | 8 ++++++-- > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c > > index e6d32c536781..a3b557fad1fd 100644 > > --- a/drivers/usb/gadget/function/u_audio.c > > +++ b/drivers/usb/gadget/function/u_audio.c > > @@ -89,7 +89,12 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req) > > struct snd_uac_chip *uac = prm->uac; > > > > /* i/f shutting down */ > > - if (!prm->ep_enabled || req->status == -ESHUTDOWN) > > + if (!prm->ep_enabled) { > > + usb_ep_free_request(ep, req); > > + return; > > + } > > + > > + if (req->status == -ESHUTDOWN) > > return; > > > > /* > > @@ -337,7 +342,6 @@ static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep) > > for (i = 0; i < params->req_number; i++) { > > if (prm->ureq[i].req) { > > usb_ep_dequeue(ep, prm->ureq[i].req); > > - usb_ep_free_request(ep, prm->ureq[i].req); > > Then, for normal base, eg, there is no pending request before calling > free_ep, then, where these uac request will be freed? We can see in this driver that prm->ureq[i].req != NULL will only be true from either u_audio_start_capture() or u_audio_start_playback() where after allocating the request it is immediately queued. So generally the lifetime of the request is tied to its queued/pending status. But you bring up a good point, it's possible usb_ep_queue() could have failed so we have to take care of the potential memory leak since the completion wouldn't get called. We should do free_request() either when ep_queue() fails or when ep_dequeue() returns error. Do you have any preference? I'm leaning toward catching it here in free_ep() as it's only one call site to take care of instead of two ;-) Thanks, Jack -- The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project