From patchwork Thu Nov 2 20:19:39 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Avichal Rakesh X-Patchwork-Id: 741220 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 E7E2821A1B for ; Thu, 2 Nov 2023 20:19:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="nlKaeGTU" Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5144193 for ; Thu, 2 Nov 2023 13:19:52 -0700 (PDT) Received: by mail-pg1-x549.google.com with SMTP id 41be03b00d2f7-5b9615ecd47so1056612a12.1 for ; Thu, 02 Nov 2023 13:19:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698956392; x=1699561192; 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=dl0Y8kXtO+v5DMU4xYXsBrmdbPzQql7yPD++RjWhQ4E=; b=nlKaeGTUSQCfg9d96sm3atrqvoFeKBdMT2yOUW68OGH4lsyOi9rDS378oUD29FE5rV YLtlnJNvzvPvYAceykY0oaDh6LD4I2LV2h6tG9bZUv1dvW7KiTGCjjaPgCp4HueMwcaK cHH3qrUTCdghfYiIqjY5s7JNT522Hn+IS9yXnVH8kv/X6k4cM7hLcRzO5l1ewLLZlkvr WktfNHBys4paUdmjsa5Pl4GlUDolyc/GYHEs1QNT1fgr1SIFQlTZUg57E3Vq/fz7y1rW 51u1vDKYa3QvH3V8NC7Zpg5M92V0OwDGnCT+ksdj079fhxIiDi9Lm5/+bNk3KZ5quNdi Howg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698956392; x=1699561192; 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=dl0Y8kXtO+v5DMU4xYXsBrmdbPzQql7yPD++RjWhQ4E=; b=oPkyAR3xPN3Z6cHAjZg+DEIi2O3KgM3L2JhhZMcj6JfTnZgLNjBAjcpidCQybk+RES OgbywwYbCtmhAttYXYU9wU4qujVevlWGhDrj8658irG9RLiXl8Akl85tCWDZ8EwY6qd1 +dG3sCp2YAR6UvjZagITJtWN3H+cdObbyWurbd9WoUbuuTO7ZcMCoN6kr8V2ZAisRHZv 2QSqRHiaj8tqbZ9nCwVWmxXoYsU6SghgKjAOWqm27F2Nu0F1L1pGFDuZMasL+apbampI KrPXj08ElwyVyIIYSs8MEOomvHxTMCzbRUWSFTLuoC1EISeYCq81/g7Q42AP0Vs2K4uH Sllg== X-Gm-Message-State: AOJu0Yx4R7eT/V+ciN+1ZlgAsLNXrp4eufrFvjcRf01mkvZGmPuzyFNY jVjo8jM9epJGSfbceLY1q/tsxtEu60CH X-Google-Smtp-Source: AGHT+IEEUZvvd3dcvOAz88QEM4qIYsDivG6jper6ykLB8PnKWfuGV4tILxmJe28/rTI5Pn1M6qzRfhfAcJYH X-Received: from hi-h2o-specialist.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:3cef]) (user=arakesh job=sendgmr) by 2002:a65:6a84:0:b0:5ab:7d1d:3322 with SMTP id q4-20020a656a84000000b005ab7d1d3322mr378503pgu.9.1698956391992; Thu, 02 Nov 2023 13:19:51 -0700 (PDT) Date: Thu, 2 Nov 2023 13:19:39 -0700 In-Reply-To: <20231102201939.4171214-1-arakesh@google.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <73309396-3856-43a2-9a6f-81a40ed594db@google.com> <20231102201939.4171214-1-arakesh@google.com> X-Mailer: git-send-email 2.42.0.869.gea05f2083d-goog Message-ID: <20231102201939.4171214-4-arakesh@google.com> Subject: [PATCH v11 4/4] usb: gadget: uvc: Fix use-after-free for inflight usb_requests From: Avichal Rakesh To: arakesh@google.com, dan.scally@ideasonboard.com Cc: etalvala@google.com, gregkh@linuxfoundation.org, jchowdhary@google.com, laurent.pinchart@ideasonboard.com, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, m.grzeschik@pengutronix.de 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_video to track when frames and requests should be flowing. When disabling the video stream, the flag is tripped and, instead of de-allocating all uvc_requests and usb_requests, the gadget driver only de-allocates those usb_requests that are currently owned by it (as present in req_free). Other usb_requests are left untouched until their completion handler is called which takes care of freeing the usb_request and its corresponding uvc_request. Now that uvc_video does not depends on uvc->state, this patch removes unnecessary upates to uvc->state that were made to accommodate uvc_video logic. 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 Reviewed-by: Michael Grzeschik Suggested-by: Michael Grzeschik Tested-by: Michael Grzeschik Signed-off-by: Avichal Rakesh Reviewed-by: Daniel Scally --- v1 -> v2 : Rebased to ToT, and fixed deadlock reported in https://lore.kernel.org/all/ZRv2UnKztgyqk2pt@pengutronix.de/ v2 -> v3 : Fix email threading goof-up v3 -> v4 : re-rebase to ToT & moved to a uvc_video level lock as discussed in https://lore.kernel.org/b14b296f-2e08-4edf-aeea-1c5b621e2d0c@google.com/ v4 -> v5 : Address review comments. Add Reviewed-by & Tested-by. v5 -> v6 : Added another patch before this one to make uvcg_video_disable easier to review. v6 -> v7 : Fix warning reported in https://lore.kernel.org/202310200457.GwPPFuHX-lkp@intel.com/ v7 -> v8 : No change. Getting back in review queue v8 -> v9 : No change. v9 -> v10 : Address review comments. Rebase to ToT (usb-next) v10 -> v11 : Address review comments drivers/usb/gadget/function/uvc.h | 1 + drivers/usb/gadget/function/uvc_v4l2.c | 10 +- drivers/usb/gadget/function/uvc_video.c | 130 ++++++++++++++++++++---- 3 files changed, 112 insertions(+), 29 deletions(-) -- 2.42.0.869.gea05f2083d-goog diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h index 993694da0bbc..be0d012aa244 100644 --- a/drivers/usb/gadget/function/uvc.h +++ b/drivers/usb/gadget/function/uvc.h @@ -102,6 +102,7 @@ struct uvc_video { unsigned int uvc_num_requests; /* Requests */ + bool is_enabled; /* tracks whether video stream is enabled */ unsigned int req_size; struct list_head ureqs; /* all uvc_requests allocated by uvc_video */ struct list_head req_free; diff --git a/drivers/usb/gadget/function/uvc_v4l2.c b/drivers/usb/gadget/function/uvc_v4l2.c index 904dd283cbf7..c7e5fa4f29e0 100644 --- a/drivers/usb/gadget/function/uvc_v4l2.c +++ b/drivers/usb/gadget/function/uvc_v4l2.c @@ -468,11 +468,11 @@ uvc_v4l2_streamoff(struct file *file, void *fh, enum v4l2_buf_type type) if (type != video->queue.queue.type) return -EINVAL; - uvc->state = UVC_STATE_CONNECTED; ret = uvcg_video_disable(video); if (ret < 0) return ret; + uvc->state = UVC_STATE_CONNECTED; uvc_function_setup_continue(uvc, 1); return 0; } @@ -507,14 +507,6 @@ uvc_v4l2_subscribe_event(struct v4l2_fh *fh, static void uvc_v4l2_disable(struct uvc_device *uvc) { uvc_function_disconnect(uvc); - /* - * Drop uvc->state to CONNECTED if it was streaming before. - * This ensures that the usb_requests are no longer queued - * to the controller. - */ - if (uvc->state == UVC_STATE_STREAMING) - uvc->state = UVC_STATE_CONNECTED; - uvcg_video_disable(&uvc->video); uvcg_free_buffers(&uvc->video.queue); uvc->func_connected = false; diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c index c3e8c48f46a9..164bdeb7f2a9 100644 --- a/drivers/usb/gadget/function/uvc_video.c +++ b/drivers/usb/gadget/function/uvc_video.c @@ -227,6 +227,10 @@ uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video, * Request handling */ +/* + * Callers must take care to hold req_lock when this function may be called + * from multiple threads. For example, when frames are streaming to the host. + */ static void uvc_video_free_request(struct uvc_request *ureq, struct usb_ep *ep) { @@ -271,9 +275,26 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req) struct uvc_request *ureq = req->context; 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; + spin_lock_irqsave(&video->req_lock, flags); + if (!video->is_enabled) { + /* + * When is_enabled is false, uvcg_video_disable() ensures + * that in-flight uvc_buffers are returned, so we can + * safely call free_request without worrying about + * last_buf. + */ + uvc_video_free_request(ureq, ep); + spin_unlock_irqrestore(&video->req_lock, flags); + return; + } + + last_buf = ureq->last_buf; + ureq->last_buf = NULL; + spin_unlock_irqrestore(&video->req_lock, flags); + switch (req->status) { case 0: break; @@ -295,17 +316,26 @@ 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(&queue->irqlock, flags); + uvcg_complete_buffer(queue, last_buf); + spin_unlock_irqrestore(&queue->irqlock, flags); } spin_lock_irqsave(&video->req_lock, flags); - list_add_tail(&req->list, &video->req_free); - spin_unlock_irqrestore(&video->req_lock, flags); - - if (uvc->state == UVC_STATE_STREAMING) + /* + * Video stream might have been disabled while we were + * processing the current usb_request. So make sure + * we're still streaming before queueing the usb_request + * back to req_free + */ + if (video->is_enabled) { + list_add_tail(&req->list, &video->req_free); queue_work(video->async_wq, &video->pump); + } else { + uvc_video_free_request(ureq, ep); + } + spin_unlock_irqrestore(&video->req_lock, flags); } static int @@ -392,20 +422,22 @@ static void uvcg_video_pump(struct work_struct *work) struct uvc_video_queue *queue = &video->queue; /* video->max_payload_size is only set when using bulk transfer */ bool is_bulk = video->max_payload_size; - struct uvc_device *uvc = video->uvc; struct usb_request *req = NULL; struct uvc_buffer *buf; unsigned long flags; bool buf_done; int ret; - while (uvc->state == UVC_STATE_STREAMING && video->ep->enabled) { + while (true) { + if (!video->ep->enabled) + return; + /* - * Retrieve the first available USB request, protected by the - * request lock. + * Check is_enabled and retrieve the first available USB + * request, protected by the request lock. */ spin_lock_irqsave(&video->req_lock, flags); - if (list_empty(&video->req_free)) { + if (!video->is_enabled || list_empty(&video->req_free)) { spin_unlock_irqrestore(&video->req_lock, flags); return; } @@ -487,9 +519,11 @@ static void uvcg_video_pump(struct work_struct *work) return; spin_lock_irqsave(&video->req_lock, flags); - list_add_tail(&req->list, &video->req_free); + if (video->is_enabled) + list_add_tail(&req->list, &video->req_free); + else + uvc_video_free_request(req->context, video->ep); spin_unlock_irqrestore(&video->req_lock, flags); - return; } /* @@ -498,7 +532,11 @@ static void uvcg_video_pump(struct work_struct *work) int uvcg_video_disable(struct uvc_video *video) { - struct uvc_request *ureq; + unsigned long flags; + struct list_head inflight_bufs; + struct usb_request *req, *temp; + struct uvc_buffer *buf, *btemp; + struct uvc_request *ureq, *utemp; if (video->ep == NULL) { uvcg_info(&video->uvc->func, @@ -506,15 +544,58 @@ uvcg_video_disable(struct uvc_video *video) return -ENODEV; } + INIT_LIST_HEAD(&inflight_bufs); + spin_lock_irqsave(&video->req_lock, flags); + video->is_enabled = false; + + /* + * Remove any in-flight buffers from the uvc_requests + * because we want to return them before cancelling the + * queue. This ensures that we aren't stuck waiting for + * all complete callbacks to come through before disabling + * vb2 queue. + */ + list_for_each_entry(ureq, &video->ureqs, list) { + if (ureq->last_buf) { + list_add_tail(&ureq->last_buf->queue, &inflight_bufs); + ureq->last_buf = NULL; + } + } + spin_unlock_irqrestore(&video->req_lock, flags); + 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); + spin_lock_irqsave(&video->req_lock, flags); + /* + * Remove all uvc_requests from ureqs with list_del_init + * This lets uvc_video_free_request correctly identify + * if the uvc_request is attached to a list or not when freeing + * memory. + */ + list_for_each_entry_safe(ureq, utemp, &video->ureqs, list) + list_del_init(&ureq->list); + + list_for_each_entry_safe(req, temp, &video->req_free, list) { + list_del(&req->list); + uvc_video_free_request(req->context, video->ep); } - uvc_video_free_requests(video); + INIT_LIST_HEAD(&video->ureqs); + INIT_LIST_HEAD(&video->req_free); + video->req_size = 0; + spin_unlock_irqrestore(&video->req_lock, flags); + + /* + * Return all the video buffers before disabling the queue. + */ + spin_lock_irqsave(&video->queue.irqlock, flags); + list_for_each_entry_safe(buf, btemp, &inflight_bufs, queue) { + list_del(&buf->queue); + uvcg_complete_buffer(&video->queue, buf); + } + spin_unlock_irqrestore(&video->queue.irqlock, flags); + uvcg_queue_enable(&video->queue, 0); return 0; } @@ -532,6 +613,14 @@ int uvcg_video_enable(struct uvc_video *video) return -ENODEV; } + /* + * Safe to access request related fields without req_lock because + * this is the only thread currently active, and no other + * request handling thread will become active until this function + * returns. + */ + video->is_enabled = true; + if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0) return ret; @@ -557,6 +646,7 @@ int uvcg_video_enable(struct uvc_video *video) */ int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc) { + video->is_enabled = false; INIT_LIST_HEAD(&video->ureqs); INIT_LIST_HEAD(&video->req_free); spin_lock_init(&video->req_lock);