Hi Sachin,
On 09/22/2012 09:28 AM, Sachin Kamat wrote:
> It is previously assumed that 'rect' could be NULL.
> Hence add a check to print the members of 'rect' only when it is not
> NULL.
>
> Signed-off-by: Sachin Kamat<sachin.kamat@xxxxxxxxxx>
> ---
> drivers/media/i2c/s5k6aa.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/i2c/s5k6aa.c b/drivers/media/i2c/s5k6aa.c
> index 045ca7f..7531edb 100644
> --- a/drivers/media/i2c/s5k6aa.c
> +++ b/drivers/media/i2c/s5k6aa.c
> @@ -1177,8 +1177,9 @@ static int s5k6aa_get_crop(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
>
> mutex_unlock(&s5k6aa->lock);
>
> - v4l2_dbg(1, debug, sd, "Current crop rectangle: (%d,%d)/%dx%d\n",
> - rect->left, rect->top, rect->width, rect->height);
> + if (rect)
> + v4l2_dbg(1, debug, sd, "Current crop rectangle: (%d,%d)/%dx%d\n",
> + rect->left, rect->top, rect->width, rect->height);
>
> return 0;
> }
Thank you for the patch. I would attack this problem form slightly
different angle though, i.e. I would make sure __s5k6aa_get_crop_rect()
always returns valid pointer. There is similar issue in s5k6aa_set_crop().
Since crop->which is already validated in
drivers/media/v4l2-core/v4l2-subdev.c and can have only values:
V4L2_SUBDEV_FORMAT_TRY, V4L2_SUBDEV_FORMAT_ACTIVE it's safe to do
something like:
8<-------------------------------------------------------------------------
>From 724aa5f1fefcaca2dee4f75ba960a1f620400e1a Mon Sep 17 00:00:00 2001
From: Sylwester Nawrocki <sylvester.nawrocki@xxxxxxxxx>
Date: Tue, 25 Sep 2012 23:53:27 +0200
Subject: [PATCH] s5k6aa: Fix potential null pointer dereference
Make sure __s5k6aa_get_crop_rect() always returns valid pointer,
as it is assumed at the callers.
crop->which is already validated when subdev set_crop and get_crop
callbacks are called from within the v4l2-core. If it ever happens
the crop operations are called directly for some reason in kernel
space, with incorrect crop->which argument, just log it with WARN
and return reference to the TRY crop.
Reported-by: Sachin Kamat <sachin.kamat@xxxxxxxxxx>
Signed-off-by: Sylwester Nawrocki <sylvester.nawrocki@xxxxxxxxx>
---
drivers/media/i2c/s5k6aa.c | 11 ++++-------
1 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/drivers/media/i2c/s5k6aa.c b/drivers/media/i2c/s5k6aa.c
index 045ca7f..57cd4fa 100644
--- a/drivers/media/i2c/s5k6aa.c
+++ b/drivers/media/i2c/s5k6aa.c
@@ -1061,10 +1061,9 @@ __s5k6aa_get_crop_rect(struct s5k6aa *s5k6aa, struct v4l2_subdev_fh *fh,
{
if (which == V4L2_SUBDEV_FORMAT_ACTIVE)
return &s5k6aa->ccd_rect;
- if (which == V4L2_SUBDEV_FORMAT_TRY)
- return v4l2_subdev_get_try_crop(fh, 0);
- return NULL;
+ WARN_ON(which != V4L2_SUBDEV_FORMAT_TRY);
+ return v4l2_subdev_get_try_crop(fh, 0);
}
static void s5k6aa_try_format(struct s5k6aa *s5k6aa,
@@ -1169,12 +1168,10 @@ static int s5k6aa_get_crop(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
struct v4l2_rect *rect;
memset(crop->reserved, 0, sizeof(crop->reserved));
- mutex_lock(&s5k6aa->lock);
+ mutex_lock(&s5k6aa->lock);
rect = __s5k6aa_get_crop_rect(s5k6aa, fh, crop->which);
- if (rect)
- crop->rect = *rect;
-
+ crop->rect = *rect;
mutex_unlock(&s5k6aa->lock);
v4l2_dbg(1, debug, sd, "Current crop rectangle: (%d,%d)/%dx%d\n",
--
1.7.4.1
8<-------------------------------------------------------------------------
I'm going to queue this patch for 3.7.
--
Thanks,
Sylwester
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