Messages in this thread | | | Date | Sat, 4 Jan 2014 22:14:13 -0800 | From | Dmitry Torokhov <> | Subject | Re: [PATCH] [media] saa7146: fix a possible NULL pointer reference in saa7146_set_position |
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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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