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

[Rajmohan Mani]

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@xxxxxxxxxxxxxxxx>
Suggested-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>

Signed-off-by: Rajmohan Mani <rajmohan.mani@xxxxxxxxx>
---
 drivers/staging/media/ipu3/ipu3-v4l2.c | 6 ++++++
 drivers/staging/media/ipu3/ipu3.c      | 3 +++
 drivers/staging/media/ipu3/ipu3.h      | 4 ++++
 3 files changed, 13 insertions(+)

diff --git a/drivers/staging/media/ipu3/ipu3-v4l2.c b/drivers/staging/media/ipu3/ipu3-v4l2.c
index c7936032beb9..cf7e917cd0c8 100644
--- a/drivers/staging/media/ipu3/ipu3-v4l2.c
+++ b/drivers/staging/media/ipu3/ipu3-v4l2.c
@@ -507,12 +507,15 @@ static int ipu3_vb2_start_streaming(struct vb2_queue *vq, unsigned int count)
 			goto fail_stop_pipeline;
 	}
 
+	mutex_lock(&imgu->streaming_lock);
+
 	/* Start streaming of the whole pipeline now */
 	dev_dbg(dev, "IMGU streaming is ready to start");
 	r = imgu_s_stream(imgu, true);
 	if (!r)
 		imgu->streaming = true;
 
+	mutex_unlock(&imgu->streaming_lock);
 	return 0;
 
 fail_stop_pipeline:
@@ -543,6 +546,8 @@ static void ipu3_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 && ipu3_all_nodes_streaming(imgu, node)) {
 		/* Yes, really stop streaming now */
@@ -552,6 +557,7 @@ static void ipu3_vb2_stop_streaming(struct vb2_queue *vq)
 			imgu->streaming = false;
 	}
 
+	mutex_unlock(&imgu->streaming_lock);
 	ipu3_return_all_buffers(imgu, node, VB2_BUF_STATE_ERROR);
 	media_pipeline_stop(&node->vdev.entity);
 }
diff --git a/drivers/staging/media/ipu3/ipu3.c b/drivers/staging/media/ipu3/ipu3.c
index d521b3afb8b1..2daee51cd845 100644
--- a/drivers/staging/media/ipu3/ipu3.c
+++ b/drivers/staging/media/ipu3/ipu3.c
@@ -635,6 +635,7 @@ 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);
 
@@ -699,6 +700,7 @@ static int imgu_pci_probe(struct pci_dev *pci_dev,
 	ipu3_css_set_powerdown(&pci_dev->dev, imgu->base);
 out_mutex_destroy:
 	mutex_destroy(&imgu->lock);
+	mutex_destroy(&imgu->streaming_lock);
 
 	return r;
 }
@@ -716,6 +718,7 @@ static void imgu_pci_remove(struct pci_dev *pci_dev)
 	ipu3_dmamap_exit(imgu);
 	ipu3_mmu_exit(imgu->mmu);
 	mutex_destroy(&imgu->lock);
+	mutex_destroy(&imgu->streaming_lock);
 }
 
 static int __maybe_unused imgu_suspend(struct device *dev)
diff --git a/drivers/staging/media/ipu3/ipu3.h b/drivers/staging/media/ipu3/ipu3.h
index 04fc99f47ebb..f732315f0701 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;
+
 	/* Forbit streaming and buffer queuing during system suspend. */
 	atomic_t qbuf_barrier;
 	/* Indicate if system suspend take place while imgu is streaming. */
-- 
2.19.1