Commit 47e8b73b authored by harperchen's avatar harperchen Committed by Mauro Carvalho Chehab
Browse files

media: cx23885: Fix a null-ptr-deref bug in buffer_prepare() and buffer_finish() 

When the driver calls cx23885_risc_buffer() to prepare the buffer, the
function call dma_alloc_coherent may fail, resulting in a empty buffer
risc->cpu. Later when we free the buffer or access the buffer, null ptr
deref is triggered.

This bug is similar to the following one:
https://git.linuxtv.org/media_stage.git/commit/?id=2b064d91440b33fba5b452f2d1b31f13ae911d71

.

We believe the bug can be also dynamically triggered from user side.
Similarly, we fix this by checking the return value of cx23885_risc_buffer()
and the value of risc->cpu before buffer free.

Signed-off-by: default avatarharperchen <harperchen1110@gmail.com>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@kernel.org>
parent ffa331d9

drivers/media/pci/cx23885/cx23885-core.c

+3 −1
Original line number Diff line number Diff line
@@ -1325,7 +1325,9 @@ void cx23885_free_buffer(struct cx23885_dev *dev, struct cx23885_buffer *buf) 
{

	struct cx23885_riscmem *risc = &buf->risc;



	if (risc->cpu)

		dma_free_coherent(&dev->pci->dev, risc->size, risc->cpu, risc->dma);

	memset(risc, 0, sizeof(*risc));

}



static void cx23885_tsport_reg_dump(struct cx23885_tsport *port)

drivers/media/pci/cx23885/cx23885-video.c

+7 −6
Original line number Diff line number Diff line
@@ -342,6 +342,7 @@ static int queue_setup(struct vb2_queue *q, 


static int buffer_prepare(struct vb2_buffer *vb)

{

	int ret;

	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);

	struct cx23885_dev *dev = vb->vb2_queue->drv_priv;

	struct cx23885_buffer *buf =
@@ -358,12 +359,12 @@ static int buffer_prepare(struct vb2_buffer *vb) 


	switch (dev->field) {

	case V4L2_FIELD_TOP:

		cx23885_risc_buffer(dev->pci, &buf->risc,

		ret = cx23885_risc_buffer(dev->pci, &buf->risc,

				sgt->sgl, 0, UNSET,

				buf->bpl, 0, dev->height);

		break;

	case V4L2_FIELD_BOTTOM:

		cx23885_risc_buffer(dev->pci, &buf->risc,

		ret = cx23885_risc_buffer(dev->pci, &buf->risc,

				sgt->sgl, UNSET, 0,

				buf->bpl, 0, dev->height);

		break;
@@ -391,21 +392,21 @@ static int buffer_prepare(struct vb2_buffer *vb) 
			line0_offset = 0;

			line1_offset = buf->bpl;

		}

		cx23885_risc_buffer(dev->pci, &buf->risc,

		ret = cx23885_risc_buffer(dev->pci, &buf->risc,

				sgt->sgl, line0_offset,

				line1_offset,

				buf->bpl, buf->bpl,

				dev->height >> 1);

		break;

	case V4L2_FIELD_SEQ_TB:

		cx23885_risc_buffer(dev->pci, &buf->risc,

		ret = cx23885_risc_buffer(dev->pci, &buf->risc,

				sgt->sgl,

				0, buf->bpl * (dev->height >> 1),

				buf->bpl, 0,

				dev->height >> 1);

		break;

	case V4L2_FIELD_SEQ_BT:

		cx23885_risc_buffer(dev->pci, &buf->risc,

		ret = cx23885_risc_buffer(dev->pci, &buf->risc,

				sgt->sgl,

				buf->bpl * (dev->height >> 1), 0,

				buf->bpl, 0,
@@ -418,7 +419,7 @@ static int buffer_prepare(struct vb2_buffer *vb) 
		buf, buf->vb.vb2_buf.index,

		dev->width, dev->height, dev->fmt->depth, dev->fmt->fourcc,

		(unsigned long)buf->risc.dma);

	return 0;

	return ret;

}



static void buffer_finish(struct vb2_buffer *vb)