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SubjectRe: [PATCH] [media] saa7146: fix a possible NULL pointer reference in saa7146_set_position
From
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
<dmitry.torokhov@gmail.com> 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 <ethan.kernel@gmail.com>
>> ---
>> 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


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