From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 A8AF61509B4; Thu, 28 Nov 2024 22:17:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732832225; cv=none; b=aCDxvYeHCPinK+5qT6nqLo3iL3thwh59/+AK9ZtjDHORkm1TSI41AdlH7cXLbSFwhMzF0B64WLjmEJ1WjNe3amcJe9hpK5sWKqveWQ6/DBAy1rFg1ym8A92ICGbMKiTPtGlZk3HKAono4KIUa5nGYzaWD6of3Pjk7zh7vEeKU88= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732832225; c=relaxed/simple; bh=FTR/bmK0kwcRvHnwRljj1g9X29iuMKZoHvQiehuyMXU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=T2Sw6G6Tp+Uyz5A9TJQJNFkYe7XGrKQxDBvoCf5FmDs3uMF23i9lZ5eikjV7RG3gCXWerfvg/OFZk4Amvik1mhLrZh8OUe/beyxblXzeHp+CFVD2uN+M7aqc8qJ7DU4cKg9bcWpC+H4j6nP5uykQEvayqX0hHmj3zsPZpQKyw/c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=vbbC/nmJ; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="vbbC/nmJ" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 537CF526; Thu, 28 Nov 2024 23:16:35 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1732832195; bh=FTR/bmK0kwcRvHnwRljj1g9X29iuMKZoHvQiehuyMXU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vbbC/nmJOdLxXwnnhOoFVsQO3LEcuQkmQnZZwXR9O9c2LDZMIzkNYIlXlPVvABqEK IFYhHCsk5lXpGeJw+uR4yxFIq5HVURLIXXFP/mIb9rHMHpKr0XQXuj83R8cRDWs+nv X05AYBroUk18/AG6SJYW3KVYJJmYfQgGXAJ1LEsQ= Date: Fri, 29 Nov 2024 00:16:49 +0200 From: Laurent Pinchart To: Ricardo Ribalda Cc: Hans de Goede , Mauro Carvalho Chehab , Guennadi Liakhovetski , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2 1/4] media: uvcvideo: Remove dangling pointers Message-ID: <20241128221649.GE25731@pendragon.ideasonboard.com> References: <20241127-uvc-fix-async-v2-0-510aab9570dd@chromium.org> <20241127-uvc-fix-async-v2-1-510aab9570dd@chromium.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20241127-uvc-fix-async-v2-1-510aab9570dd@chromium.org> Hi Ricardo, Thank you for the patch. On Wed, Nov 27, 2024 at 12:14:49PM +0000, 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 s/). A/), a/ > 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 | 38 ++++++++++++++++++++++++++++++++++++-- > drivers/media/usb/uvc/uvc_v4l2.c | 2 ++ > drivers/media/usb/uvc/uvcvideo.h | 8 +++++++- > 3 files changed, 45 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c > index 4fe26e82e3d1..b6af4ff92cbd 100644 > --- a/drivers/media/usb/uvc/uvc_ctrl.c > +++ b/drivers/media/usb/uvc/uvc_ctrl.c > @@ -1589,7 +1589,12 @@ void uvc_ctrl_status_event(struct uvc_video_chain *chain, How about adding static void uvc_ctrl_set_handle(struct uvc_control *ctrl, uvc_fh *handle) { if (handle) { if (!ctrl->handle) handle->pending_async_ctrls++; ctrl->handle = handle; } else if (ctrl->handle) { ctrl->handle = NULL; if (!WARN_ON(!handle->pending_async_ctrls)) handle->pending_async_ctrls--; } } > mutex_lock(&chain->ctrl_mutex); > > handle = ctrl->handle; > - ctrl->handle = NULL; > + if (handle) { > + ctrl->handle = NULL; > + WARN_ON(!handle->pending_async_ctrls); > + if (handle->pending_async_ctrls) > + handle->pending_async_ctrls--; > + } This would become handle = ctrl->handle; uvc_ctrl_set_handle(ctrl, NULL); > > list_for_each_entry(mapping, &ctrl->info.mappings, list) { > s32 value = __uvc_ctrl_get_value(mapping, data); > @@ -2046,8 +2051,11 @@ int uvc_ctrl_set(struct uvc_fh *handle, > mapping->set(mapping, value, > uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT)); > > - if (ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS) > + if (ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS) { > + if (!ctrl->handle) > + handle->pending_async_ctrls++; > ctrl->handle = handle; > + } Here if (ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS) uvc_ctrl_set_handle(ctrl, handle); > > ctrl->dirty = 1; > ctrl->modified = 1; > @@ -2770,6 +2778,32 @@ 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) { > + struct uvc_control *ctrl = &entity->controls[i]; > + > + if (ctrl->handle != handle) > + continue; > + > + ctrl->handle = NULL; > + if (WARN_ON(!handle->pending_async_ctrls)) > + continue; > + handle->pending_async_ctrls--; And here uvc_ctrl_set_handle(ctrl, NULL); It seems less error-prone to centralize the logic. I'd add a lockdep_assert() in uvc_ctrl_set_handle(), but there's no easy access to the chain there. > + } > + } > + > + 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..c68659b70221 100644 > --- a/drivers/media/usb/uvc/uvcvideo.h > +++ b/drivers/media/usb/uvc/uvcvideo.h > @@ -337,7 +337,10 @@ 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 and > + * uvc_fh.pending_async_ctrls > + */ > > struct v4l2_prio_state prio; /* V4L2 priority state */ > u32 caps; /* V4L2 chain-wide caps */ > @@ -612,6 +615,7 @@ 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 +801,8 @@ 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); -- Regards, Laurent Pinchart