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.
Signed-off-by: Wenwen Wang <[email protected]>
---
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);
--
2.7.4
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 <[email protected]>
> ---
> 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 <[email protected]>
Intel Finland Oy