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

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Submitter rajmohan.mani@intel.com
Date Jan. 29, 2019, 10:27 p.m.
Message ID <20190129222736.6216-1-rajmohan.mani@intel.com>
Download mbox | patch
Permalink /patch/54214/
State Changes Requested
Headers show

Comments

rajmohan.mani@intel.com - Jan. 29, 2019, 10:27 p.m.
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>
---
 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(+)
Sakari Ailus - Jan. 30, 2019, 8:59 a.m.
Hi Rajmohan,

On Tue, Jan 29, 2019 at 02:27:36PM -0800, Rajmohan Mani 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>
> ---
>  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);
> +

You appear to be using imgu_device.lock (while searching buffers to queue
to the device) as well as imgu_video_device.lock (qbuf, dqbuf) to serialise
access to imgu_video_device.buffers list. The two locks may be acquired at
the same time but each by different processes. That needs to be addressed,
but probably not in this patch.

I wonder if it'd be more simple to use imgu->lock here instead of adding a
new one.

>  	/* 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. */
rajmohan.mani@intel.com - Jan. 30, 2019, 5:17 p.m.
Hi Sakari,

> -----Original Message-----
> From: Sakari Ailus [mailto:sakari.ailus@linux.intel.com]
> Sent: Wednesday, January 30, 2019 12:59 AM
> To: Mani, Rajmohan <rajmohan.mani@intel.com>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>; Greg Kroah-Hartman
> <gregkh@linuxfoundation.org>; linux-media@vger.kernel.org;
> devel@driverdev.osuosl.org; linux-kernel@vger.kernel.org; Laurent Pinchart
> <laurent.pinchart@ideasonboard.com>; Jacopo Mondi <jacopo@jmondi.org>;
> Qiu, Tian Shu <tian.shu.qiu@intel.com>; Cao, Bingbu
> <bingbu.cao@intel.com>; Zhi@paasikivi.fi.intel.com; Zhi, Yong
> <yong.zhi@intel.com>; hverkuil@xs4all.nl; tfiga@chromium.org
> Subject: Re: [PATCH] media: staging/intel-ipu3: Implement lock for stream
> on/off operations
> 
> Hi Rajmohan,
> 
> On Tue, Jan 29, 2019 at 02:27:36PM -0800, Rajmohan Mani 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>
> > ---
> >  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);
> > +
> 
> You appear to be using imgu_device.lock (while searching buffers to queue to
> the device) as well as imgu_video_device.lock (qbuf, dqbuf) to serialise access
> to imgu_video_device.buffers list.

Ack

> The two locks may be acquired at the same
> time but each by different processes. That needs to be addressed, but
> probably not in this patch.
> 

The node specific locks will be used by different processes and all of these processes
will be competing commonly (and successfully) for the imgu_device lock.
I will look into this more.

> I wonder if it'd be more simple to use imgu->lock here instead of adding a new
> one.
> 

Extending imgu->lock here, does not work in this case, as imgu_queue_buffers()
will be stuck acquiring imgu->lock, which was already acquired by imgu_s_stream()
through ipu3_vb2_start_streaming().

> >  	/* 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. */
> 
> --
> Regards,
> 
> Sakari Ailus
> sakari.ailus@linux.intel.com
Sakari Ailus - Jan. 31, 2019, 12:18 p.m.
Hi Raj,

On Wed, Jan 30, 2019 at 05:17:15PM +0000, Mani, Rajmohan wrote:
> Hi Sakari,
> 
> > -----Original Message-----
> > From: Sakari Ailus [mailto:sakari.ailus@linux.intel.com]
> > Sent: Wednesday, January 30, 2019 12:59 AM
> > To: Mani, Rajmohan <rajmohan.mani@intel.com>
> > Cc: Mauro Carvalho Chehab <mchehab@kernel.org>; Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org>; linux-media@vger.kernel.org;
> > devel@driverdev.osuosl.org; linux-kernel@vger.kernel.org; Laurent Pinchart
> > <laurent.pinchart@ideasonboard.com>; Jacopo Mondi <jacopo@jmondi.org>;
> > Qiu, Tian Shu <tian.shu.qiu@intel.com>; Cao, Bingbu
> > <bingbu.cao@intel.com>; Zhi@paasikivi.fi.intel.com; Zhi, Yong
> > <yong.zhi@intel.com>; hverkuil@xs4all.nl; tfiga@chromium.org
> > Subject: Re: [PATCH] media: staging/intel-ipu3: Implement lock for stream
> > on/off operations
> > 
> > Hi Rajmohan,
> > 
> > On Tue, Jan 29, 2019 at 02:27:36PM -0800, Rajmohan Mani 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>
> > > ---
> > >  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);
> > > +
> > 
> > You appear to be using imgu_device.lock (while searching buffers to queue to
> > the device) as well as imgu_video_device.lock (qbuf, dqbuf) to serialise access
> > to imgu_video_device.buffers list.
> 
> Ack
> 
> > The two locks may be acquired at the same
> > time but each by different processes. That needs to be addressed, but
> > probably not in this patch.
> > 
> 
> The node specific locks will be used by different processes and all of these processes
> will be competing commonly (and successfully) for the imgu_device lock.
> I will look into this more.

Oops. I think I must have misread something; looking at the code again,
indeed imgu_device.lock is acquired for all accesses. Please ignore this
comment.

> 
> > I wonder if it'd be more simple to use imgu->lock here instead of adding a new
> > one.
> > 
> 
> Extending imgu->lock here, does not work in this case, as imgu_queue_buffers()
> will be stuck acquiring imgu->lock, which was already acquired by imgu_s_stream()
> through ipu3_vb2_start_streaming().
> 
> > >  	/* 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. */
> > 
> > --
> > Regards,
> > 
> > Sakari Ailus
> > sakari.ailus@linux.intel.com
rajmohan.mani@intel.com - Feb. 1, 2019, 7:13 p.m.
Hi Sakari,

> Subject: Re: [PATCH] media: staging/intel-ipu3: Implement lock for stream
> on/off operations
> 
> Hi Raj,
> 
> On Wed, Jan 30, 2019 at 05:17:15PM +0000, Mani, Rajmohan wrote:
> > Hi Sakari,
> >
> > > -----Original Message-----
> > > From: Sakari Ailus [mailto:sakari.ailus@linux.intel.com]
> > > Sent: Wednesday, January 30, 2019 12:59 AM
> > > To: Mani, Rajmohan <rajmohan.mani@intel.com>
> > > Cc: Mauro Carvalho Chehab <mchehab@kernel.org>; Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org>; linux-media@vger.kernel.org;
> > > devel@driverdev.osuosl.org; linux-kernel@vger.kernel.org; Laurent
> > > Pinchart <laurent.pinchart@ideasonboard.com>; Jacopo Mondi
> > > <jacopo@jmondi.org>; Qiu, Tian Shu <tian.shu.qiu@intel.com>; Cao,
> > > Bingbu <bingbu.cao@intel.com>; Zhi@paasikivi.fi.intel.com; Zhi, Yong
> > > <yong.zhi@intel.com>; hverkuil@xs4all.nl; tfiga@chromium.org
> > > Subject: Re: [PATCH] media: staging/intel-ipu3: Implement lock for
> > > stream on/off operations
> > >
> > > Hi Rajmohan,
> > >
> > > On Tue, Jan 29, 2019 at 02:27:36PM -0800, Rajmohan Mani 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>
> > > > ---
> > > >  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);
> > > > +
> > >
> > > You appear to be using imgu_device.lock (while searching buffers to
> > > queue to the device) as well as imgu_video_device.lock (qbuf, dqbuf)
> > > to serialise access to imgu_video_device.buffers list.
> >
> > Ack
> >
> > > The two locks may be acquired at the same time but each by different
> > > processes. That needs to be addressed, but probably not in this
> > > patch.
> > >
> >
> > The node specific locks will be used by different processes and all of
> > these processes will be competing commonly (and successfully) for the
> imgu_device lock.
> > I will look into this more.
> >
> > > I wonder if it'd be more simple to use imgu->lock here instead of
> > > adding a new one.
> > >
> >
> > Extending imgu->lock here, does not work in this case, as
> > imgu_queue_buffers() will be stuck acquiring imgu->lock, which was
> > already acquired by imgu_s_stream() through ipu3_vb2_start_streaming().
> 
> You could move acquiring the lock out of these functions. It would also seem
> that there is device-wide streaming state etc. information to which the access
> should also be serialised. Currently it's relying on the node-specific lock only
> which does not help.
> 

Ack. Let me look into this more.

> Can you grab the lock right after dev_dbg() line in the function?
> 

In order to reduce the amount of code that's run with the lock held,
I placed the lock here.

Do you see issues in calls to imgu_sd subdevs and media_pipeline_start(),
without the lock being held?

> The lock should be also acquired before testing imgu->streaming in
> ipu3_vb2_buf_queue() to make sure it won't change in the meantime.
> 

I thought about this and decided against this since the odds of multiple
instances of applications, each of which using a single node simultaneously
are less, in a typical camera use case.
Please confirm if you see significant issues without the lock here, so we can
add the lock here as well.

> >
> > > >  	/* 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);
> 
> I'd also call ipu3_return_all_buffers() before releasing the lock: in principle the
> user may have queued new buffers on the devices before the driver marks the
> buffers as faulty.
> 
> > >
> > > >  	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. */
> > >
> 
> --
> Sakari Ailus
> sakari.ailus@linux.intel.com
rajmohan.mani@intel.com - Feb. 4, 2019, 5:43 p.m.
Hi Sakari,

[snip]

> > > > >  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);
> >
> > I'd also call ipu3_return_all_buffers() before releasing the lock: in
> > principle the user may have queued new buffers on the devices before
> > the driver marks the buffers as faulty.
> >

Ack
(Somehow I missed this comment.)

[snip]

Patch

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. */

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