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Mon, 02 Dec 2024 06:44:01 -0800 (PST) X-Google-Smtp-Source: AGHT+IEWF4PANTV7QM9gmc9vOIQsZ+o2QQHXMvTVA4aaxxEJKtLVDAOhFJn+aQIj3fgeQcZdoiUR2A== X-Received: by 2002:a05:6402:2743:b0:5d0:e568:7ba1 with SMTP id 4fb4d7f45d1cf-5d0e5688804mr6842979a12.30.1733150641274; Mon, 02 Dec 2024 06:44:01 -0800 (PST) Received: from [10.40.98.157] ([78.108.130.194]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5d0c6999e45sm3391302a12.52.2024.12.02.06.44.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Dec 2024 06:44:00 -0800 (PST) Message-ID: <79da5e62-acb0-4bf5-a1c0-f2000fae0167@redhat.com> Date: Mon, 2 Dec 2024 15:44:00 +0100 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 2/5] media: uvcvideo: Remove dangling pointers To: Ricardo Ribalda , Laurent Pinchart , Mauro Carvalho Chehab , Guennadi Liakhovetski Cc: Hans Verkuil , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20241202-uvc-fix-async-v5-0-6658c1fe312b@chromium.org> <20241202-uvc-fix-async-v5-2-6658c1fe312b@chromium.org> Content-Language: en-US From: Hans de Goede In-Reply-To: <20241202-uvc-fix-async-v5-2-6658c1fe312b@chromium.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, On 2-Dec-24 3:24 PM, Ricardo Ribalda wrote: > When an async control is written, we copy a pointer to the file handle > that started the operation. That pointer will be used when the device is > done. Which could be anytime in the future. > > If the user closes that file descriptor, its structure will be freed, > and there will be one dangling pointer per pending async control, that > the driver will try to use. > > Clean all the dangling pointers during release(). > > To avoid adding a performance penalty in the most common case (no async > operation), a counter has been introduced with some logic to make sure > that it is properly handled. > > Cc: stable@vger.kernel.org > Fixes: e5225c820c05 ("media: uvcvideo: Send a control event when a Control Change interrupt arrives") > Signed-off-by: Ricardo Ribalda > --- > drivers/media/usb/uvc/uvc_ctrl.c | 52 ++++++++++++++++++++++++++++++++++++++-- > drivers/media/usb/uvc/uvc_v4l2.c | 2 ++ > drivers/media/usb/uvc/uvcvideo.h | 9 ++++++- > 3 files changed, 60 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c > index 9a80a7d8e73a..af1e38f5c6e9 100644 > --- a/drivers/media/usb/uvc/uvc_ctrl.c > +++ b/drivers/media/usb/uvc/uvc_ctrl.c > @@ -1579,6 +1579,37 @@ static void uvc_ctrl_send_slave_event(struct uvc_video_chain *chain, > uvc_ctrl_send_event(chain, handle, ctrl, mapping, val, changes); > } > > +static void uvc_ctrl_get_handle(struct uvc_fh *handle, struct uvc_control *ctrl) > +{ > + lockdep_assert_held(&handle->chain->ctrl_mutex); > + > + if (ctrl->handle) > + dev_warn_ratelimited(&handle->stream->dev->udev->dev, > + "UVC non compliance: Setting an async control with a pending operation."); > + > + if (handle == ctrl->handle) > + return; > + > + if (ctrl->handle) > + ctrl->handle->pending_async_ctrls--; > + > + ctrl->handle = handle; > + handle->pending_async_ctrls++; > +} Maybe simplify this to: static void uvc_ctrl_get_handle(struct uvc_fh *handle, struct uvc_control *ctrl) { lockdep_assert_held(&handle->chain->ctrl_mutex); if (!ctrl->handle) handle->pending_async_ctrls++; else dev_warn_ratelimited(&handle->stream->dev->udev->dev, "UVC non compliance: Setting an async control with a pending operation."); ctrl->handle = handle; } ? Otherwise the patch looks good to me: Reviewed-by: Hans de Goede Regards, Hans > +static void uvc_ctrl_put_handle(struct uvc_fh *handle, struct uvc_control *ctrl) > +{ > + lockdep_assert_held(&handle->chain->ctrl_mutex); > + > + if (ctrl->handle != handle) /* Nothing to do here.*/ > + return; > + > + ctrl->handle = NULL; > + if (WARN_ON(!handle->pending_async_ctrls)) > + return; > + handle->pending_async_ctrls--; > +} > + > void uvc_ctrl_status_event(struct uvc_video_chain *chain, > struct uvc_control *ctrl, const u8 *data) > { > @@ -1589,7 +1620,8 @@ void uvc_ctrl_status_event(struct uvc_video_chain *chain, > mutex_lock(&chain->ctrl_mutex); > > handle = ctrl->handle; > - ctrl->handle = NULL; > + if (handle) > + uvc_ctrl_put_handle(handle, ctrl); > > list_for_each_entry(mapping, &ctrl->info.mappings, list) { > s32 value = __uvc_ctrl_get_value(mapping, data); > @@ -1865,7 +1897,7 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev, > > if (!rollback && handle && > ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS) > - ctrl->handle = handle; > + uvc_ctrl_get_handle(handle, ctrl); > } > > return 0; > @@ -2774,6 +2806,22 @@ int uvc_ctrl_init_device(struct uvc_device *dev) > return 0; > } > > +void uvc_ctrl_cleanup_fh(struct uvc_fh *handle) > +{ > + struct uvc_entity *entity; > + > + guard(mutex)(&handle->chain->ctrl_mutex); > + > + if (!handle->pending_async_ctrls) > + return; > + > + list_for_each_entry(entity, &handle->chain->dev->entities, list) > + for (unsigned int i = 0; i < entity->ncontrols; ++i) > + uvc_ctrl_put_handle(handle, &entity->controls[i]); > + > + WARN_ON(handle->pending_async_ctrls); > +} > + > /* > * Cleanup device controls. > */ > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c > index 97c5407f6603..b425306a3b8c 100644 > --- a/drivers/media/usb/uvc/uvc_v4l2.c > +++ b/drivers/media/usb/uvc/uvc_v4l2.c > @@ -652,6 +652,8 @@ static int uvc_v4l2_release(struct file *file) > > uvc_dbg(stream->dev, CALLS, "%s\n", __func__); > > + uvc_ctrl_cleanup_fh(handle); > + > /* Only free resources if this is a privileged handle. */ > if (uvc_has_privileges(handle)) > uvc_queue_release(&stream->queue); > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h > index 07f9921d83f2..92ecdd188587 100644 > --- a/drivers/media/usb/uvc/uvcvideo.h > +++ b/drivers/media/usb/uvc/uvcvideo.h > @@ -337,7 +337,11 @@ struct uvc_video_chain { > struct uvc_entity *processing; /* Processing unit */ > struct uvc_entity *selector; /* Selector unit */ > > - struct mutex ctrl_mutex; /* Protects ctrl.info */ > + struct mutex ctrl_mutex; /* > + * Protects ctrl.info, > + * ctrl.handle and > + * uvc_fh.pending_async_ctrls > + */ > > struct v4l2_prio_state prio; /* V4L2 priority state */ > u32 caps; /* V4L2 chain-wide caps */ > @@ -612,6 +616,7 @@ struct uvc_fh { > struct uvc_video_chain *chain; > struct uvc_streaming *stream; > enum uvc_handle_state state; > + unsigned int pending_async_ctrls; > }; > > struct uvc_driver { > @@ -797,6 +802,8 @@ int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id, > int uvc_xu_ctrl_query(struct uvc_video_chain *chain, > struct uvc_xu_control_query *xqry); > > +void uvc_ctrl_cleanup_fh(struct uvc_fh *handle); > + > /* Utility functions */ > struct usb_host_endpoint *uvc_find_endpoint(struct usb_host_interface *alts, > u8 epaddr); >