From nobody Thu Jan 8 07:38:43 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EAC79E71D55 for ; Sat, 30 Sep 2023 18:48:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234627AbjI3Ssp (ORCPT ); Sat, 30 Sep 2023 14:48:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234751AbjI3Ssn (ORCPT ); Sat, 30 Sep 2023 14:48:43 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 111C0100 for ; Sat, 30 Sep 2023 11:48:39 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-59f6902dc8bso215755367b3.0 for ; Sat, 30 Sep 2023 11:48:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1696099718; x=1696704518; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=8sS0/uaQLhAvse+d/NY7S3JtHJHgQXnCXFHZHAD5jYQ=; b=tRLc6bqBTUC+HjWpMuM+lJSzMX7JOeSi+5VjDfx965ORJh4k2dXGYvpooRLZTa5g2f o/6cYNB6pXGXw+DCQoQXyCxfrGz8oQW6bkTbAxP1rlO7l1cQp4i8L+NZ/Yl8u4FhG+WB Bkb4S9gRWR04NGOJMishgCr4Jbzi3OF+ePmmajq+efN53iurJvUIUVT1v6D11kKRP8nY RZl/4CP6Qlxfk5ZmiiPAs4s1hi6nG4lOhJq3YuctxnKiMqhL50tNTmRpTp5SJFO/2bhL RsDbJXpNVrmCElhY2PHGbGaP9tjPTVxBzJze0umhW8G+/omiQnNzZriw4XqCNxP1ybJW 2vmQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696099718; x=1696704518; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=8sS0/uaQLhAvse+d/NY7S3JtHJHgQXnCXFHZHAD5jYQ=; b=fYwe6FwzyAylKg7gydbZwJF3hQIhmG92G4kc2lCdX7eXBosMPg9+bbVg5yX1vL+Muk xAubc/X2vb2bJKy2olmRUg1X1bwCTGCwLM2x1PVrMJwdRA/C/OmLVgZ8jUigBmzuD0jz WRdM2EZW1hwnJ0ATUpU9C2M5i23yiC4dQiw8Xs7KFl+d0Va3W+10YGkpCedt2JbxWMla bg9B6ExZC2Ag5hJkHI3ioREHyY2wHg10j9UvC2Di0B4y32SfxEoJEzuB5K2Uraie6f2i OAYiJbFtnsxSiPa4tv7EX+SVGuzhpW21ZUttB/ZzexEoCMGFYXvyfHimDnPsO3kMD9HH 4CHw== X-Gm-Message-State: AOJu0Yz8PI3jsyUn2qLbtwGEOBikT8GrpWDHRqD9cfQuZkJoo3XQO9mV fNZ/WEw53gHikYVhoEt6rpuAjO/AdZKp X-Google-Smtp-Source: AGHT+IHWdhL5RAVxsyWTiI4/e6dqT9qBN4mYpBbtKdY2IFEu9Ctuxp7yzyHR+CXeMVVBwlqF+9X+xO7MZ7h0 X-Received: from hi-h2o-specialist.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:3cef]) (user=arakesh job=sendgmr) by 2002:a05:690c:3412:b0:579:f832:74b with SMTP id fn18-20020a05690c341200b00579f832074bmr130768ywb.10.1696099718241; Sat, 30 Sep 2023 11:48:38 -0700 (PDT) Date: Sat, 30 Sep 2023 11:48:21 -0700 In-Reply-To: <20230930184821.310143-1-arakesh@google.com> Mime-Version: 1.0 References: <20230930184821.310143-1-arakesh@google.com> X-Mailer: git-send-email 2.42.0.582.g8ccd20d70d-goog Message-ID: <20230930184821.310143-4-arakesh@google.com> Subject: [PATCH v1 3/3] usb: gadget: uvc: Fix use-after-free for inflight usb_requests From: Avichal Rakesh To: Laurent Pinchart , Daniel Scally , Greg Kroah-Hartman , Michael Grzeschik Cc: jchowdhary@google.com, etalvala@google.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Avichal Rakesh , Michael Grzeschik Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Currently, the uvc gadget driver allocates all uvc_requests as one array and deallocates them all when the video stream stops. This includes de-allocating all the usb_requests associated with those uvc_requests. This can lead to use-after-free issues if any of those de-allocated usb_requests were still owned by the usb controller. This is patch 2 of 2 in fixing the use-after-free issue. It adds a new flag to uvc_request to mark it as 'abandoned'. When disabling the video stream, instead of de-allocating all uvc_requests and usb_requests, the gadget driver only de-allocates those usb_requests that are currently owned by the gadget driver (as present in req_free). Other usb_requests have their corresponding 'is_abandoned' flag tripped, and the usb_requests complete handler takes care of freeing the usb_request and its corresponding uvc_request. This should ensure that uvc gadget driver never accidentally de-allocates a usb_request that it doesn't own. Link: https://lore.kernel.org/7cd81649-2795-45b6-8c10-b7df1055020d@google.c= om Suggested-by: Michael Grzeschik Signed-off-by: Avichal Rakesh --- drivers/usb/gadget/function/uvc.h | 1 + drivers/usb/gadget/function/uvc_video.c | 106 ++++++++++++++++++++---- 2 files changed, 91 insertions(+), 16 deletions(-) diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/functio= n/uvc.h index 993694da0bbc..e69cfb7cced1 100644 --- a/drivers/usb/gadget/function/uvc.h +++ b/drivers/usb/gadget/function/uvc.h @@ -82,6 +82,7 @@ struct uvc_request { u8 header[UVCG_REQUEST_HEADER_LEN]; struct uvc_buffer *last_buf; struct list_head list; + bool is_abandoned; }; =20 struct uvc_video { diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/f= unction/uvc_video.c index ffecd7a140dc..aad7dcba46ee 100644 --- a/drivers/usb/gadget/function/uvc_video.c +++ b/drivers/usb/gadget/function/uvc_video.c @@ -271,7 +271,21 @@ uvc_video_complete(struct usb_ep *ep, struct usb_reque= st *req) struct uvc_video *video =3D ureq->video; struct uvc_video_queue *queue =3D &video->queue; struct uvc_device *uvc =3D video->uvc; + struct uvc_buffer *last_buf; unsigned long flags; + bool is_abandoned; + + spin_lock_irqsave(&video->req_lock, flags); + is_abandoned =3D ureq->is_abandoned; + last_buf =3D ureq->last_buf; + ureq->last_buf =3D NULL; + spin_unlock_irqrestore(&video->req_lock, flags); + + if (is_abandoned) { + uvcg_dbg(&video->uvc->func, "Freeing abandoned usb_request\n"); + uvc_video_free_request(ureq, ep); + return; + } =20 switch (req->status) { case 0: @@ -294,15 +308,29 @@ uvc_video_complete(struct usb_ep *ep, struct usb_requ= est *req) uvcg_queue_cancel(queue, 0); } =20 - if (ureq->last_buf) { - uvcg_complete_buffer(&video->queue, ureq->last_buf); - ureq->last_buf =3D NULL; + if (last_buf) { + spin_lock_irqsave(&video->queue.irqlock, flags); + uvcg_complete_buffer(&video->queue, last_buf); + spin_unlock_irqrestore(&video->queue.irqlock, flags); } =20 + /* + * request might have been abandoned while being processed. + * do a last minute check before queueing the request back. + */ spin_lock_irqsave(&video->req_lock, flags); - list_add_tail(&req->list, &video->req_free); + is_abandoned =3D ureq->is_abandoned; + if (!is_abandoned) + list_add_tail(&req->list, &video->req_free); spin_unlock_irqrestore(&video->req_lock, flags); =20 + if (is_abandoned) { + uvcg_dbg(&video->uvc->func, + "usb_request abandoned mid-processing - freeing.\n"); + uvc_video_free_request(ureq, ep); + return; + } + if (uvc->state =3D=3D UVC_STATE_STREAMING) queue_work(video->async_wq, &video->pump); } @@ -366,7 +394,6 @@ uvc_video_alloc_requests(struct uvc_video *video) } =20 video->req_size =3D req_size; - return 0; =20 error: @@ -490,13 +517,69 @@ static void uvcg_video_pump(struct work_struct *work) return; } =20 +/* + * Disable video stream. This ensures that any inflight usb requests are m= arked + * for clean up and all video buffers are dropped before returning. + */ +static void uvcg_video_disable(struct uvc_video *video) +{ + struct uvc_buffer *buf, *tmp_buf; + struct uvc_request *ureq, *temp; + struct list_head buf_list; /* track in-flight video buffers */ + struct usb_request *req; + unsigned long flags; + + cancel_work_sync(&video->pump); + uvcg_queue_cancel(&video->queue, 0); + + INIT_LIST_HEAD(&buf_list); + spin_lock_irqsave(&video->req_lock, flags); + /* abandon all usb requests */ + list_for_each_entry_safe(ureq, temp, &video->ureqs, list) { + ureq->is_abandoned =3D true; + if (ureq->last_buf) { + list_add(&ureq->last_buf->queue, &buf_list); + ureq->last_buf =3D NULL; + } + list_del_init(&ureq->list); + if (ureq->req) + usb_ep_dequeue(video->ep, ureq->req); + } + /* + * re-add uvc_requests currently owned by the gadget to + * video->ureqs to be deallocated + */ + list_for_each_entry(req, &video->req_free, list) { + ureq =3D req->context; + list_add_tail(&ureq->list, &video->ureqs); + } + spin_unlock_irqrestore(&video->req_lock, flags); + + /* + * drop abandoned uvc_buffers, as the completion handler + * no longer will + */ + if (!list_empty(&buf_list)) { + spin_lock_irqsave(&video->queue.irqlock, flags); + list_for_each_entry_safe(buf, tmp_buf, + &buf_list, queue) { + video->queue.flags |=3D UVC_QUEUE_DROP_INCOMPLETE; + uvcg_complete_buffer(&video->queue, buf); + list_del(&buf->queue); + } + spin_unlock_irqrestore(&video->queue.irqlock, flags); + } + + uvc_video_free_requests(video); + uvcg_queue_enable(&video->queue, 0); +} + /* * Enable or disable the video stream. */ int uvcg_video_enable(struct uvc_video *video, int enable) { int ret; - struct uvc_request *ureq; =20 if (video->ep =3D=3D NULL) { uvcg_info(&video->uvc->func, @@ -505,16 +588,7 @@ int uvcg_video_enable(struct uvc_video *video, int ena= ble) } =20 if (!enable) { - cancel_work_sync(&video->pump); - uvcg_queue_cancel(&video->queue, 0); - - list_for_each_entry(ureq, &video->ureqs, list) { - if (ureq->req) - usb_ep_dequeue(video->ep, ureq->req); - } - - uvc_video_free_requests(video); - uvcg_queue_enable(&video->queue, 0); + uvcg_video_disable(video); return 0; } =20 --=20 2.42.0.582.g8ccd20d70d-goog