From patchwork Tue May 25 04:29:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jack Pham X-Patchwork-Id: 12277783 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=-16.8 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,URIBL_BLOCKED,USER_AGENT_GIT 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 D4A25C47084 for ; Tue, 25 May 2021 04:29:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B1F5761408 for ; Tue, 25 May 2021 04:29:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230406AbhEYEbT (ORCPT ); Tue, 25 May 2021 00:31:19 -0400 Received: from m43-7.mailgun.net ([69.72.43.7]:15164 "EHLO m43-7.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229476AbhEYEbS (ORCPT ); Tue, 25 May 2021 00:31:18 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1621916989; h=Content-Transfer-Encoding: MIME-Version: Message-Id: Date: Subject: Cc: To: From: Sender; bh=oCutuukYs7uGs5rzLn8jFX89efaAqNYl7cu3djw/fGs=; b=v15o4e1AtLJFuD92UVev7mFjNty3zRQHqyQWzDJRHvKEJFMXeHLou/MtcQk8lpCad9Knn/r1 5+u0qcS6lJO+bmuTN7g5g70Ll8IrtZC1Vz87u58IbXY86OfAaFi4T9+ylZcS32VI5BQmY4d0 u5Ywq3LV/Ea9g88c0xmegyfnwlU= X-Mailgun-Sending-Ip: 69.72.43.7 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-n04.prod.us-east-1.postgun.com with SMTP id 60ac7d3d8dd30e785fde5867 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 25 May 2021 04:29:49 GMT Sender: jackp=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 83BB4C4323A; Tue, 25 May 2021 04:29:48 +0000 (UTC) Received: from jackp-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: jackp) by smtp.codeaurora.org (Postfix) with ESMTPSA id 8EE31C433D3; Tue, 25 May 2021 04:29:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 8EE31C433D3 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 From: Jack Pham To: Felipe Balbi , Greg Kroah-Hartman Cc: Peter Chen , Wesley Cheng , linux-usb@vger.kernel.org, Jack Pham , stable@vger.kernel.org Subject: [PATCH] usb: dwc3: gadget: Bail from dwc3_gadget_exit() if dwc->gadget is NULL Date: Mon, 24 May 2021 21:29:22 -0700 Message-Id: <20210525042922.15591-1-jackp@codeaurora.org> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org 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. - 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 --- 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);