Re: [PATCH v2] media: staging/intel-ipu3: Implement lock for stream on/off operations

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Bingbu,

On Thu, Mar 26, 2020 at 05:16:30PM +0800, Bingbu Cao wrote:
> Currently concurrent stream off operations on ImgU nodes are not
> synchronized, leading to use-after-free bugs (as reported by KASAN).
> 
> [  250.090724] BUG: KASAN: use-after-free in
> ipu3_dmamap_free+0xc5/0x116 [ipu3_imgu]
> [  250.090726] Read of size 8 at addr ffff888127b29bc0 by task
> yavta/18836
> [  250.090731] Hardware name: HP Soraka/Soraka, BIOS
> Google_Soraka.10431.17.0 03/22/2018
> [  250.090732] Call Trace:
> [  250.090735]  dump_stack+0x6a/0xb1
> [  250.090739]  print_address_description+0x8e/0x279
> [  250.090743]  ? ipu3_dmamap_free+0xc5/0x116 [ipu3_imgu]
> [  250.090746]  kasan_report+0x260/0x28a
> [  250.090750]  ipu3_dmamap_free+0xc5/0x116 [ipu3_imgu]
> [  250.090754]  ipu3_css_pool_cleanup+0x24/0x37 [ipu3_imgu]
> [  250.090759]  ipu3_css_pipeline_cleanup+0x61/0xb9 [ipu3_imgu]
> [  250.090763]  ipu3_css_stop_streaming+0x1f2/0x321 [ipu3_imgu]
> [  250.090768]  imgu_s_stream+0x94/0x443 [ipu3_imgu]
> [  250.090772]  ? ipu3_vb2_buf_queue+0x280/0x280 [ipu3_imgu]
> [  250.090775]  ? vb2_dma_sg_unmap_dmabuf+0x16/0x6f [videobuf2_dma_sg]
> [  250.090778]  ? vb2_buffer_in_use+0x36/0x58 [videobuf2_common]
> [  250.090782]  ipu3_vb2_stop_streaming+0xf9/0x135 [ipu3_imgu]
> 
> Implemented a lock to synchronize imgu stream on / off operations and
> the modification of streaming flag (in struct imgu_device), to prevent
> these issues.
> 
> Reported-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Rajmohan Mani <rajmohan.mani@intel.com>
> Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
> ---
>  drivers/staging/media/ipu3/ipu3-v4l2.c | 9 +++++++++
>  drivers/staging/media/ipu3/ipu3.c      | 3 +++
>  drivers/staging/media/ipu3/ipu3.h      | 4 ++++
>  3 files changed, 16 insertions(+)
> 
> diff --git a/drivers/staging/media/ipu3/ipu3-v4l2.c b/drivers/staging/media/ipu3/ipu3-v4l2.c
> index 09c8ede1457c..0358d0998314 100644
> --- a/drivers/staging/media/ipu3/ipu3-v4l2.c
> +++ b/drivers/staging/media/ipu3/ipu3-v4l2.c
> @@ -367,8 +367,10 @@ static void imgu_vb2_buf_queue(struct vb2_buffer *vb)
>  
>  	vb2_set_plane_payload(vb, 0, need_bytes);
>  
> +	mutex_lock(&imgu->streaming_lock);
>  	if (imgu->streaming)
>  		imgu_queue_buffers(imgu, false, node->pipe);
> +	mutex_unlock(&imgu->streaming_lock);
>  
>  	dev_dbg(&imgu->pci_dev->dev, "%s for pipe %u node %u", __func__,
>  		node->pipe, node->id);
> @@ -468,10 +470,12 @@ static int imgu_vb2_start_streaming(struct vb2_queue *vq, unsigned int count)
>  	dev_dbg(dev, "%s node name %s pipe %u id %u", __func__,
>  		node->name, node->pipe, node->id);
>  
> +	mutex_lock(&imgu->streaming_lock);
>  	if (imgu->streaming) {
>  		r = -EBUSY;

mutex_unlock() here.

Apart from that this seems fine.

>  		goto fail_return_bufs;
>  	}
> +	mutex_unlock(&imgu->streaming_lock);
>  
>  	if (!node->enabled) {
>  		dev_err(dev, "IMGU node is not enabled");
> @@ -498,9 +502,11 @@ static int imgu_vb2_start_streaming(struct vb2_queue *vq, unsigned int count)
>  
>  	/* Start streaming of the whole pipeline now */
>  	dev_dbg(dev, "IMGU streaming is ready to start");
> +	mutex_lock(&imgu->streaming_lock);
>  	r = imgu_s_stream(imgu, true);
>  	if (!r)
>  		imgu->streaming = true;
> +	mutex_unlock(&imgu->streaming_lock);
>  
>  	return 0;
>  
> @@ -532,6 +538,7 @@ static void imgu_vb2_stop_streaming(struct vb2_queue *vq)
>  		dev_err(&imgu->pci_dev->dev,
>  			"failed to stop subdev streaming\n");
>  
> +	mutex_lock(&imgu->streaming_lock);
>  	/* Was this the first node with streaming disabled? */
>  	if (imgu->streaming && imgu_all_nodes_streaming(imgu, node)) {
>  		/* Yes, really stop streaming now */
> @@ -542,6 +549,8 @@ static void imgu_vb2_stop_streaming(struct vb2_queue *vq)
>  	}
>  
>  	imgu_return_all_buffers(imgu, node, VB2_BUF_STATE_ERROR);
> +	mutex_unlock(&imgu->streaming_lock);
> +
>  	media_pipeline_stop(&node->vdev.entity);
>  }
>  
> diff --git a/drivers/staging/media/ipu3/ipu3.c b/drivers/staging/media/ipu3/ipu3.c
> index 4d53aad31483..a25a997cfd7e 100644
> --- a/drivers/staging/media/ipu3/ipu3.c
> +++ b/drivers/staging/media/ipu3/ipu3.c
> @@ -675,6 +675,7 @@ static int imgu_pci_probe(struct pci_dev *pci_dev,
>  		return r;
>  
>  	mutex_init(&imgu->lock);
> +	mutex_init(&imgu->streaming_lock);
>  	atomic_set(&imgu->qbuf_barrier, 0);
>  	init_waitqueue_head(&imgu->buf_drain_wq);
>  
> @@ -738,6 +739,7 @@ static int imgu_pci_probe(struct pci_dev *pci_dev,
>  out_css_powerdown:
>  	imgu_css_set_powerdown(&pci_dev->dev, imgu->base);
>  out_mutex_destroy:
> +	mutex_destroy(&imgu->streaming_lock);
>  	mutex_destroy(&imgu->lock);
>  
>  	return r;
> @@ -755,6 +757,7 @@ static void imgu_pci_remove(struct pci_dev *pci_dev)
>  	imgu_css_set_powerdown(&pci_dev->dev, imgu->base);
>  	imgu_dmamap_exit(imgu);
>  	imgu_mmu_exit(imgu->mmu);
> +	mutex_destroy(&imgu->streaming_lock);
>  	mutex_destroy(&imgu->lock);
>  }
>  
> diff --git a/drivers/staging/media/ipu3/ipu3.h b/drivers/staging/media/ipu3/ipu3.h
> index 73b123b2b8a2..8cd6a0077d99 100644
> --- a/drivers/staging/media/ipu3/ipu3.h
> +++ b/drivers/staging/media/ipu3/ipu3.h
> @@ -146,6 +146,10 @@ struct imgu_device {
>  	 * vid_buf.list and css->queue
>  	 */
>  	struct mutex lock;
> +
> +	/* Lock to protect writes to streaming flag in this struct */
> +	struct mutex streaming_lock;
> +
>  	/* Forbid streaming and buffer queuing during system suspend. */
>  	atomic_t qbuf_barrier;
>  	/* Indicate if system suspend take place while imgu is streaming. */

-- 
Kind regards,

Sakari Ailus