media: staging/intel-ipu3: Implement lock for stream on/off operations

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>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

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 +470,13 @@ 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(&imgu->streaming_lock);
 		goto fail_return_bufs;
 	}
+	mutex_unlock(&imgu->streaming_lock);
 
 	if (!node->enabled) {
 		dev_err(dev, "IMGU node is not enabled");
@@ -498,9 +503,11 @@ 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 +539,7 @@ 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 +550,8 @@ 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);
 }
 

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);
 }
 

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. */