2014-01-05 02:08:26

by ethan zhao

Subject: [PATCH] [media] saa7146: fix a possible NULL pointer reference in saa7146_set_position

Function saa7146_format_by_fourcc() may return NULL, reference of the returned
result would cause NULL pointer issue without checking.

Signed-off-by: Ethan Zhao <[email protected]>
---
drivers/media/common/saa7146/saa7146_hlp.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/media/common/saa7146/saa7146_hlp.c b/drivers/media/common/saa7146/saa7146_hlp.c
index be746d1..3e23eab 100644
--- a/drivers/media/common/saa7146/saa7146_hlp.c
+++ b/drivers/media/common/saa7146/saa7146_hlp.c
@@ -575,6 +575,7 @@ static void saa7146_set_position(struct saa7146_dev *dev, int w_x, int w_y, int
*/
u32 base = (u32)(unsigned long)vv->ov_fb.base;

+ int which = 1;
struct saa7146_video_dma vdma1;

/* calculate memory offsets for picture, look if we shall top-down-flip */
@@ -608,10 +609,14 @@ static void saa7146_set_position(struct saa7146_dev *dev, int w_x, int w_y, int
vdma1.pitch *= -1;
}

- vdma1.base_page = sfmt->swap;
+ if (sfmt)
+ vdma1.base_page = sfmt->swap;
+ else
+ which = 0;
+
vdma1.num_line_byte = (vv->standard->v_field<<16)+vv->standard->h_pixels;

- saa7146_write_out_dma(dev, 1, &vdma1);
+ saa7146_write_out_dma(dev, which, &vdma1);
}

static void saa7146_set_output_format(struct saa7146_dev *dev, unsigned long palette)
--
1.8.3.4 (Apple Git-47)

2014-01-05 06:14:18

by Dmitry Torokhov

Subject: Re: [PATCH] [media] saa7146: fix a possible NULL pointer reference in saa7146_set_position

On Sun, Jan 05, 2014 at 10:08:00AM +0800, Ethan Zhao wrote:
> Function saa7146_format_by_fourcc() may return NULL, reference of the returned
> result would cause NULL pointer issue without checking.
>
> Signed-off-by: Ethan Zhao <[email protected]>
> ---
> drivers/media/common/saa7146/saa7146_hlp.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/common/saa7146/saa7146_hlp.c b/drivers/media/common/saa7146/saa7146_hlp.c
> index be746d1..3e23eab 100644
> --- a/drivers/media/common/saa7146/saa7146_hlp.c
> +++ b/drivers/media/common/saa7146/saa7146_hlp.c
> @@ -575,6 +575,7 @@ static void saa7146_set_position(struct saa7146_dev *dev, int w_x, int w_y, int
> */
> u32 base = (u32)(unsigned long)vv->ov_fb.base;
>
> + int which = 1;
> struct saa7146_video_dma vdma1;
>
> /* calculate memory offsets for picture, look if we shall top-down-flip */
> @@ -608,10 +609,14 @@ static void saa7146_set_position(struct saa7146_dev *dev, int w_x, int w_y, int
> vdma1.pitch *= -1;
> }
>
> - vdma1.base_page = sfmt->swap;
> + if (sfmt)
> + vdma1.base_page = sfmt->swap;
> + else
> + which = 0;
> +
> vdma1.num_line_byte = (vv->standard->v_field<<16)+vv->standard->h_pixels;
>
> - saa7146_write_out_dma(dev, 1, &vdma1);
> + saa7146_write_out_dma(dev, which, &vdma1);

If saa7146_format_by_fourcc() returns NULL you'll crash much earlier
when trying to do

int depth = sfmt->depth;

I am not familiar with the code by it seems you are papering over the
problem. Will we ever get here with unknown pixel format?

Thanks.

--
Dmitry

2014-01-06 05:47:06

by ethan zhao

Subject: Re: [PATCH] [media] saa7146: fix a possible NULL pointer reference in saa7146_set_position

Dmitry,
Yup,thank you point out that, need NULL pointer checking in
calculate_video_dma_grab_packed() , I am not familiar with saa7146
too. wouldn't paper over it, just a fix to pass code review.

Thanks,
Ethan

On Sun, Jan 5, 2014 at 2:14 PM, Dmitry Torokhov
<[email protected]> wrote:
> On Sun, Jan 05, 2014 at 10:08:00AM +0800, Ethan Zhao wrote:
>> Function saa7146_format_by_fourcc() may return NULL, reference of the returned
>> result would cause NULL pointer issue without checking.
>>
>> Signed-off-by: Ethan Zhao <[email protected]>
>> ---
>> drivers/media/common/saa7146/saa7146_hlp.c | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/common/saa7146/saa7146_hlp.c b/drivers/media/common/saa7146/saa7146_hlp.c
>> index be746d1..3e23eab 100644
>> --- a/drivers/media/common/saa7146/saa7146_hlp.c
>> +++ b/drivers/media/common/saa7146/saa7146_hlp.c
>> @@ -575,6 +575,7 @@ static void saa7146_set_position(struct saa7146_dev *dev, int w_x, int w_y, int
>> */
>> u32 base = (u32)(unsigned long)vv->ov_fb.base;
>>
>> + int which = 1;
>> struct saa7146_video_dma vdma1;
>>
>> /* calculate memory offsets for picture, look if we shall top-down-flip */
>> @@ -608,10 +609,14 @@ static void saa7146_set_position(struct saa7146_dev *dev, int w_x, int w_y, int
>> vdma1.pitch *= -1;
>> }
>>
>> - vdma1.base_page = sfmt->swap;
>> + if (sfmt)
>> + vdma1.base_page = sfmt->swap;
>> + else
>> + which = 0;
>> +
>> vdma1.num_line_byte = (vv->standard->v_field<<16)+vv->standard->h_pixels;
>>
>> - saa7146_write_out_dma(dev, 1, &vdma1);
>> + saa7146_write_out_dma(dev, which, &vdma1);
>
> If saa7146_format_by_fourcc() returns NULL you'll crash much earlier
> when trying to do
>
> int depth = sfmt->depth;
>
> I am not familiar with the code by it seems you are papering over the
> problem. Will we ever get here with unknown pixel format?
>
> Thanks.
>
> --
> Dmitry