From patchwork Tue Oct 3 23:21:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Avichal Rakesh X-Patchwork-Id: 13408080 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DAFBE3FB04 for ; Tue, 3 Oct 2023 23:21:26 +0000 (UTC) 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 C11E3B0 for ; Tue, 3 Oct 2023 16:21:23 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5a1df5b7830so21518867b3.1 for ; Tue, 03 Oct 2023 16:21:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1696375283; x=1696980083; 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=xX0umRmiZ0cLGmGD38f/MibuOBTvqO+eaoVVtdmVDCY=; b=nd4Vi0j/kzWHsBJ17zftBwdc6C/M7Msob9+RgKP5gBZxYSHK3vfmFbpJ0RncMTgpu/ R6RGKa8jBe96fK3O+YKKvkxGJipEsMkwQrQLTV9xPytZcHP6R91aON1heMWcSG+boVmF CUkQpvyVhDReZWgzmuOo2/v+kvleNInOiWsIq+LL3Ss/9D+tQK/prAMsH5ur6kyAHOPy H12705hfVo5Z7kchSOvXhxHCOALaS/hH6xNlYF6rKHuQOTBnYrnEIosYkAJMqX61MbTP W5w52YKfbRhj6+c9qlzr8fteVsxli236ZXDKHtkrehs3YogjxT4OzIacA+t6Fr4VyXZV 8MJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696375283; x=1696980083; 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=xX0umRmiZ0cLGmGD38f/MibuOBTvqO+eaoVVtdmVDCY=; b=pIBEhMJRTv1tR84WQDMHmQ/nsy0OXFGF9RUQKWoCqQji9uaSestxI34UowCz7Xp/Bg cVT4P/mK64B0IkwBLeZs6rXhY5GKUrfV4U3Pc2zT9kzMzkP7vS0RLUOuOo3rZQAygft8 1d7PVoQN0o8/BIoQCK1QrdiAnzuNjIFkXGGEzvOppeoq/lIzcoZXNKzppIv0ELCUrU6w Bxh/NlWayrrH9CeN8clCO46/VaN/4unjLYKtCniILA7qrVgriCuuZKl4P+8OOi2JIaud XT1Tgz1bY2xM5KRUrjeEIIklvFpG4+4N4O3q6LHQ8bdkwpCpQjHgGQBD7Nx9ccVNObjU QlNg== X-Gm-Message-State: AOJu0Yzd7Sm34ZjjWsB+cMJZrRqiCg6rWJU44ubHwtJLhOCTxsSH9qke 2vgUbSNVafhw6VL7+YuuoDwPrsnRNmnQ X-Google-Smtp-Source: AGHT+IGSrWanjAkruP+Az1MmmFYTVYaT8bPHGsJb3wfDLC5Ra2CutV+dDmO/2/x+1U3Y1LlA5xpJrA9Ay0LN X-Received: from hi-h2o-specialist.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:3cef]) (user=arakesh job=sendgmr) by 2002:a81:b3c3:0:b0:59b:eb63:4beb with SMTP id r186-20020a81b3c3000000b0059beb634bebmr18764ywh.7.1696375283016; Tue, 03 Oct 2023 16:21:23 -0700 (PDT) Date: Tue, 3 Oct 2023 16:21:20 -0700 In-Reply-To: <20230930184821.310143-4-arakesh@google.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20230930184821.310143-4-arakesh@google.com> X-Mailer: git-send-email 2.42.0.582.g8ccd20d70d-goog Message-ID: <20231003232120.2594176-1-arakesh@google.com> Subject: [PATCH v2 3/3] usb: gadget: uvc: Fix use-after-free for inflight usb_requests From: Avichal Rakesh To: arakesh@google.com, dan.scally@ideasonboard.com, gregkh@linuxfoundation.org, laurent.pinchart@ideasonboard.com, m.grzeschik@pengutronix.de, mgr@pengutronix.de Cc: etalvala@google.com, jchowdhary@google.com, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net 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.com Suggested-by: Michael Grzeschik Signed-off-by: Avichal Rakesh --- v1 -> v2: Rebased to ToT, and fixed deadlock reported in https://lore.kernel.org/all/ZRv2UnKztgyqk2pt@pengutronix.de/ drivers/usb/gadget/function/uvc.h | 1 + drivers/usb/gadget/function/uvc_video.c | 118 ++++++++++++++++++++---- 2 files changed, 102 insertions(+), 17 deletions(-) -- 2.42.0.582.g8ccd20d70d-goog diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/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; }; struct uvc_video { diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c index 3c4d286d81c0..69521886d599 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_request *req) struct uvc_video *video = ureq->video; struct uvc_video_queue *queue = &video->queue; struct uvc_device *uvc = video->uvc; + struct uvc_buffer *last_buf; unsigned long flags; + bool is_abandoned; + + spin_lock_irqsave(&video->req_lock, flags); + is_abandoned = ureq->is_abandoned; + last_buf = ureq->last_buf; + ureq->last_buf = 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; + } if (uvc->state == UVC_STATE_CONNECTED) { usb_ep_free_request(video->ep, ureq->req); @@ -300,15 +314,29 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req) uvcg_queue_cancel(queue, 0); } - if (ureq->last_buf) { - uvcg_complete_buffer(&video->queue, ureq->last_buf); - ureq->last_buf = 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); } + /* + * 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 = ureq->is_abandoned; + if (!is_abandoned) + list_add_tail(&req->list, &video->req_free); spin_unlock_irqrestore(&video->req_lock, flags); + 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 == UVC_STATE_STREAMING) queue_work(video->async_wq, &video->pump); } @@ -372,7 +400,6 @@ uvc_video_alloc_requests(struct uvc_video *video) } video->req_size = req_size; - return 0; error: @@ -504,13 +531,80 @@ static void uvcg_video_pump(struct work_struct *work) return; } +/* + * Disable video stream. This ensures that any inflight usb requests are marked + * 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; + + INIT_LIST_HEAD(&buf_list); + + 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); + } + + /** + * acquiring req_lock here should prevent any more complete + * callbacks from processing until we've abandoned the + * requests that are still in-flight and let the complete + * callback handle cleanup + */ + spin_lock_irqsave(&video->req_lock, flags); + /* abandon all usb requests */ + list_for_each_entry_safe(ureq, temp, &video->ureqs, list) { + ureq->is_abandoned = true; + if (ureq->last_buf) { + list_add(&ureq->last_buf->queue, &buf_list); + ureq->last_buf = NULL; + } + list_del_init(&ureq->list); + } + /* + * re-add uvc_requests currently owned by the gadget to + * video->ureqs to be deallocated. This effectively leaves + * video->ureqs with the requests that we currently own. + */ + list_for_each_entry(req, &video->req_free, list) { + ureq = 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 |= 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) { struct uvc_device *uvc = video->uvc; - struct uvc_request *ureq; int ret; if (video->ep == NULL) { @@ -521,17 +615,7 @@ int uvcg_video_enable(struct uvc_video *video, int enable) if (!enable) { uvc->state = UVC_STATE_CONNECTED; - - 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; }