On Fri, 2018-05-04 at 02:29 -0500, Wenwen Wang wrote: > At the end of atomisp_subdev_set_selection(), the function > atomisp_subdev_get_rect() is invoked to get the pointer to v4l2_rect. > Since > this function may return a NULL pointer, it is firstly invoked to > check > the returned pointer. If the returned pointer is not NULL, then the > function is invoked again to obtain the pointer and the memory content > at the location of the returned pointer is copied to the memory > location of > r. In most cases, the pointers returned by the two invocations are > same. > However, given that the pointer returned by the function > atomisp_subdev_get_rect() is not a constant, it is possible that the > two > invocations return two different pointers. For example, another thread > may > race to modify the related pointers during the two invocations. In > that > case, even if the first returned pointer is not null, the second > returned > pointer might be null, which will cause issues such as null pointer > dereference. > > This patch saves the pointer returned by the first invocation and > removes > the second invocation. If the returned pointer is not NULL, the memory > content is copied according to the original code. > The driver will be gone soon, don't bother with it anymore. Thanks! > Signed-off-by: Wenwen Wang <wang6495@xxxxxxx> > --- > drivers/staging/media/atomisp/pci/atomisp2/atomisp_subdev.c | 6 ++++- > - > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git > a/drivers/staging/media/atomisp/pci/atomisp2/atomisp_subdev.c > b/drivers/staging/media/atomisp/pci/atomisp2/atomisp_subdev.c > index 49a9973..d5fa513 100644 > --- a/drivers/staging/media/atomisp/pci/atomisp2/atomisp_subdev.c > +++ b/drivers/staging/media/atomisp/pci/atomisp2/atomisp_subdev.c > @@ -366,6 +366,7 @@ int atomisp_subdev_set_selection(struct > v4l2_subdev *sd, > unsigned int i; > unsigned int padding_w = pad_w; > unsigned int padding_h = pad_h; > + struct v4l2_rect *p; > > stream_id = atomisp_source_pad_to_stream_id(isp_sd, > vdev_pad); > > @@ -536,9 +537,10 @@ int atomisp_subdev_set_selection(struct > v4l2_subdev *sd, > ffmt[pad]->height = comp[pad]->height; > } > > - if (!atomisp_subdev_get_rect(sd, cfg, which, pad, target)) > + p = atomisp_subdev_get_rect(sd, cfg, which, pad, target); > + if (!p) > return -EINVAL; > - *r = *atomisp_subdev_get_rect(sd, cfg, which, pad, target); > + *r = *p; > > dev_dbg(isp->dev, "sel actual: l %d t %d w %d h %d\n", > r->left, r->top, r->width, r->height); -- Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Intel Finland Oy
