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 E3BD21DB34E; Tue, 3 Dec 2024 20:36:10 +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=1733258174; cv=none; b=WJEICjFaSumciJuHLNysgZPDScIS9afielHPTvbaBZOXhC1LsB2mCVVR3mltBA1X9zPBQnS3w327dgrfgeoULBQYfdk8AHLQJQWv18KF55ehTwHITISY89mbvzvvFQb2onLSEkGAZ8/a87za5CXb4ZVPQdGznDI1k84aJLbtOb4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733258174; c=relaxed/simple; bh=4Waxk1OrNO6GTFs5DQaMfzgQ3SOLEn10SlKSkxh4Wqw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=A1ouv4HwwpJiNwBBtTMd1dxxxwIj/DgSQWnAJkxIoqIaxteAGiktmQDEk5IwNT7uat2411Tla86cs0q7x1/4zHxhbU7U+Ojhb28TCQrMx6T15ZqlFfKZE+J1PhpyPdv1qVWr9tlVBE8WXmZgryi41Rwv50KAWEOZVaxrV2nLYPQ= 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=gTLWXnnR; 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="gTLWXnnR" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 64865670; Tue, 3 Dec 2024 21:35:41 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1733258141; bh=4Waxk1OrNO6GTFs5DQaMfzgQ3SOLEn10SlKSkxh4Wqw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gTLWXnnRHlD/aULJBcJfMgCX1Aiwui4OhNloCG5ZGnfFARmqFxHR5mzxT6hbVfzpH EYHQ7g3jUTm3SBXv6E2+ToDBIuzzix6Tgx8XzJ+PfyrXFc0rmGvwc+6PR5VdxyWliP Ybne+jhjC04jfD25h2XPbWrp4bBXafcWw6U5wv40= Date: Tue, 3 Dec 2024 22:35:57 +0200 From: Laurent Pinchart To: Ricardo Ribalda Cc: Hans de Goede , Mauro Carvalho Chehab , Guennadi Liakhovetski , Hans Verkuil , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v5 2/5] media: uvcvideo: Remove dangling pointers Message-ID: <20241203203557.GC5196@pendragon.ideasonboard.com> References: <20241202-uvc-fix-async-v5-0-6658c1fe312b@chromium.org> <20241202-uvc-fix-async-v5-2-6658c1fe312b@chromium.org> Precedence: bulk X-Mailing-List: stable@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: <20241202-uvc-fix-async-v5-2-6658c1fe312b@chromium.org> Hi Ricardo, Thank you for the patch. On Mon, Dec 02, 2024 at 02:24:36PM +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 > 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++; > +} > + > +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--; > +} get/put have strong connotations in the kernel, related to acquiring a reference to a given object, and releasing it. The usage here is different, and I think it makes the usage below confusing. I prefer the original single function. > + > 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) 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); > -- Regards, Laurent Pinchart