[PATCH AUTOSEL 5.15 02/47] media: cx88: Fix a null-ptr-deref bug in buffer_prepare()

Sasha Levin
2022-10-13T00:31:02Z

From: Zheyu Ma <zheyuma97@gmail.com>

[ Upstream commit 2b064d91440b33fba5b452f2d1b31f13ae911d71 ]

When the driver calls cx88_risc_buffer() to prepare the buffer, the
function call may fail, resulting in a empty buffer and null-ptr-deref
later in buffer_queue().

The following log can reveal it:

[ 41.822762] general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
[ 41.824488] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
[ 41.828027] RIP: 0010:buffer_queue+0xc2/0x500
[ 41.836311] Call Trace:
[ 41.836945] __enqueue_in_driver+0x141/0x360
[ 41.837262] vb2_start_streaming+0x62/0x4a0
[ 41.838216] vb2_core_streamon+0x1da/0x2c0
[ 41.838516] __vb2_init_fileio+0x981/0xbc0
[ 41.839141] __vb2_perform_fileio+0xbf9/0x1120
[ 41.840072] vb2_fop_read+0x20e/0x400
[ 41.840346] v4l2_read+0x215/0x290
[ 41.840603] vfs_read+0x162/0x4c0

Fix this by checking the return value of cx88_risc_buffer()

[hverkuil: fix coding style issues]

Signed-off-by: Zheyu Ma <zheyuma97@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>
---
drivers/media/pci/cx88/cx88-vbi.c | 9 +++---
drivers/media/pci/cx88/cx88-video.c | 43 +++++++++++++++--------------
2 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/drivers/media/pci/cx88/cx88-vbi.c b/drivers/media/pci/cx88/cx88-vbi.c
index a075788c64d4..469aeaa725ad 100644
--- a/drivers/media/pci/cx88/cx88-vbi.c
+++ b/drivers/media/pci/cx88/cx88-vbi.c
@@ -144,11 +144,10 @@ static int buffer_prepare(struct vb2_buffer *vb)
return -EINVAL;
vb2_set_plane_payload(vb, 0, size);

- cx88_risc_buffer(dev->pci, &buf->risc, sgt->sgl,
- 0, VBI_LINE_LENGTH * lines,
- VBI_LINE_LENGTH, 0,
- lines);
- return 0;
+ return cx88_risc_buffer(dev->pci, &buf->risc, sgt->sgl,
+ 0, VBI_LINE_LENGTH * lines,
+ VBI_LINE_LENGTH, 0,
+ lines);
}

static void buffer_finish(struct vb2_buffer *vb)
diff --git a/drivers/media/pci/cx88/cx88-video.c b/drivers/media/pci/cx88/cx88-video.c
index c17ad9f7d822..99c55109c1e0 100644
--- a/drivers/media/pci/cx88/cx88-video.c
+++ b/drivers/media/pci/cx88/cx88-video.c
@@ -431,6 +431,7 @@ 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 cx8800_dev *dev = vb->vb2_queue->drv_priv;
struct cx88_core *core = dev->core;
@@ -445,35 +446,35 @@ static int buffer_prepare(struct vb2_buffer *vb)

switch (core->field) {
case V4L2_FIELD_TOP:
- cx88_risc_buffer(dev->pci, &buf->risc,
- sgt->sgl, 0, UNSET,
- buf->bpl, 0, core->height);
+ ret = cx88_risc_buffer(dev->pci, &buf->risc,
+ sgt->sgl, 0, UNSET,
+ buf->bpl, 0, core->height);
break;
case V4L2_FIELD_BOTTOM:
- cx88_risc_buffer(dev->pci, &buf->risc,
- sgt->sgl, UNSET, 0,
- buf->bpl, 0, core->height);
+ ret = cx88_risc_buffer(dev->pci, &buf->risc,
+ sgt->sgl, UNSET, 0,
+ buf->bpl, 0, core->height);
break;
case V4L2_FIELD_SEQ_TB:
- cx88_risc_buffer(dev->pci, &buf->risc,
- sgt->sgl,
- 0, buf->bpl * (core->height >> 1),
- buf->bpl, 0,
- core->height >> 1);
+ ret = cx88_risc_buffer(dev->pci, &buf->risc,
+ sgt->sgl,
+ 0, buf->bpl * (core->height >> 1),
+ buf->bpl, 0,
+ core->height >> 1);
break;
case V4L2_FIELD_SEQ_BT:
- cx88_risc_buffer(dev->pci, &buf->risc,
- sgt->sgl,
- buf->bpl * (core->height >> 1), 0,
- buf->bpl, 0,
- core->height >> 1);
+ ret = cx88_risc_buffer(dev->pci, &buf->risc,
+ sgt->sgl,
+ buf->bpl * (core->height >> 1), 0,
+ buf->bpl, 0,
+ core->height >> 1);
break;
case V4L2_FIELD_INTERLACED:
default:
- cx88_risc_buffer(dev->pci, &buf->risc,
- sgt->sgl, 0, buf->bpl,
- buf->bpl, buf->bpl,
- core->height >> 1);
+ ret = cx88_risc_buffer(dev->pci, &buf->risc,
+ sgt->sgl, 0, buf->bpl,
+ buf->bpl, buf->bpl,
+ core->height >> 1);
break;
}
dprintk(2,
@@ -481,7 +482,7 @@ static int buffer_prepare(struct vb2_buffer *vb)
buf, buf->vb.vb2_buf.index, __func__,
core->width, core->height, dev->fmt->depth, dev->fmt->fourcc,
(unsigned long)buf->risc.dma);
- return 0;
+ return ret;
}

static void buffer_finish(struct vb2_buffer *vb)
--
2.35.1