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=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 53673C4708C for ; Fri, 28 May 2021 04:55:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22A55613DD for ; Fri, 28 May 2021 04:55:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232936AbhE1E5W (ORCPT ); Fri, 28 May 2021 00:57:22 -0400 Received: from m43-7.mailgun.net ([69.72.43.7]:41131 "EHLO m43-7.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230299AbhE1E5W (ORCPT ); Fri, 28 May 2021 00:57:22 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1622177748; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=QjyA6rEH+Y4lxZCRKVeB1fd2Js19Cr+UydtbIw/v8Gg=; b=uIxVTD3zM9RK7rRYoC0U4W0cyr3yZufhqyl53L0awsl8YcyW5h8uCgTsfjeGngWJct5ejUsV L/j47DBrMhpT4gZKhXCc7LrBHumTFiX/GnZ76sckwpnB/JWYKgkI8uD9/VC3/e9StOpXzYZ2 VFyP5lQuc0gXBlymXdWHkeFxCyQ= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyI1ZjI4MyIsICJzdGFibGVAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n05.prod.us-east-1.postgun.com with SMTP id 60b077bee27c0cc77f6ae161 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Fri, 28 May 2021 04:55:26 GMT Sender: jackp=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 82827C4338A; Fri, 28 May 2021 04:55:25 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: jackp) by smtp.codeaurora.org (Postfix) with ESMTPSA id 96EEEC433D3; Fri, 28 May 2021 04:55:24 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 27 May 2021 21:55:24 -0700 From: jackp@codeaurora.org To: Peter Chen Cc: Felipe Balbi , Greg Kroah-Hartman , Wesley Cheng , linux-usb@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] usb: dwc3: gadget: Bail from dwc3_gadget_exit() if dwc->gadget is NULL In-Reply-To: <20210528041210.GA20937@nchen> References: <20210525042922.15591-1-jackp@codeaurora.org> <20210528041210.GA20937@nchen> Message-ID: <788e5aead5b2e85b31296b15acb4a564@codeaurora.org> X-Sender: jackp@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On 2021-05-27 21:12, Peter Chen wrote: > On 21-05-24 21:29:22, Jack Pham wrote: >> There exists a possible scenario in which dwc3_gadget_init() can fail: >> during during host -> peripheral mode switch in dwc3_set_mode(), and >> a pending gadget driver fails to bind. Then, if the DRD undergoes >> another mode switch from peripheral->host the resulting >> dwc3_gadget_exit() will attempt to reference an invalid and dangling >> dwc->gadget pointer as well as call dma_free_coherent() on unmapped >> DMA pointers. >> >> The exact scenario can be reproduced as follows: >> - Start DWC3 in peripheral mode >> - Configure ConfigFS gadget with FunctionFS instance (or use g_ffs) >> - Run FunctionFS userspace application (open EPs, write descriptors, >> etc) >> - Bind gadget driver to DWC3's UDC >> - Switch DWC3 to host mode >> => dwc3_gadget_exit() is called. usb_del_gadget() will put the >> ConfigFS driver instance on the gadget_driver_pending_list >> - Stop FunctionFS application (closes the ep files) >> - Switch DWC3 to peripheral mode >> => dwc3_gadget_init() fails as usb_add_gadget() calls >> check_pending_gadget_drivers() and attempts to rebind the UDC >> to the ConfigFS gadget but fails with -19 (-ENODEV) because the >> FFS instance is not in FFS_READY state. > > There is no such state at enum ffs_state, you mean flag desc_ready is > not > true, right? Ah sorry! I meant FFS_ACTIVE, but you are also correct, it would be equivalent to ffs_dev::desc_ready. Shall I amend this commit description? >> - Switch DWC3 back to host mode >> => dwc3_gadget_exit() is called again, but this time dwc->gadget >> is invalid. >> >> Although it can be argued that userspace should take responsibility >> for ensuring that the FunctionFS application be ready prior to >> allowing the composite driver bind to the UDC, failure to do so >> should not result in a panic from the kernel driver. >> >> Fix this by setting dwc->gadget to NULL in the failure path of >> dwc3_gadget_init() and add a check to dwc3_gadget_exit() to bail out >> unless the gadget pointer is valid. >> >> Fixes: e81a7018d93a ("usb: dwc3: allocate gadget structure >> dynamically") >> Cc: >> Signed-off-by: Jack Pham > > Reviewed-by: Peter Chen Thank you Peter! >> --- >> Hi Felipe, >> >> Although I marked the 'Fixes' tag above to e81a7018d93a, the problem >> theoretically exists prior to Peter's change. But I'm not sure how >> best to fix on versions prior to this change since dwc->gadget used >> to be an embedded struct so we can't do a simple NULL check as below. >> Suggestions on alternative approaches welcome if we want to proceed >> with backporting to older (pre-5.9) stable releases. >> >> Thanks, >> Jack >> >> drivers/usb/dwc3/gadget.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c >> index 612825a39f82..65d9b7227752 100644 >> --- a/drivers/usb/dwc3/gadget.c >> +++ b/drivers/usb/dwc3/gadget.c >> @@ -4046,6 +4046,7 @@ int dwc3_gadget_init(struct dwc3 *dwc) >> dwc3_gadget_free_endpoints(dwc); >> err4: >> usb_put_gadget(dwc->gadget); >> + dwc->gadget = NULL; >> err3: >> dma_free_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE, dwc->bounce, >> dwc->bounce_addr); >> @@ -4065,6 +4066,9 @@ int dwc3_gadget_init(struct dwc3 *dwc) >> >> void dwc3_gadget_exit(struct dwc3 *dwc) >> { >> + if (!dwc->gadget) >> + return; >> + >> usb_del_gadget(dwc->gadget); >> dwc3_gadget_free_endpoints(dwc); >> usb_put_gadget(dwc->gadget); >> -- >> 2.24.0 >>