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

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[ Upstream commit 47e8b73bc35d7c54642f78e498697692f6358996 ]

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: harperchen <harperchen1110@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
harperchen 2023-03-02 13:39:05 +01:00 committed by Greg Kroah-Hartman
parent 346c975524
commit 6738841f6f
2 changed files with 10 additions and 7 deletions
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4
drivers/media/pci/cx23885/cx23885-core.c
View File

@ -1325,7 +1325,9 @@ void cx23885_free_buffer(struct cx23885_dev *dev, struct cx23885_buffer *buf)
{
struct cx23885_riscmem *risc = &buf->risc;
dma_free_coherent(&dev->pci->dev, risc->size, risc->cpu, risc->dma);
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)

13
drivers/media/pci/cx23885/cx23885-video.c
View File

@ -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)