On 18/10/2024 07:53, Mauro Carvalho Chehab wrote:
> As detected by Coverity, the error check logic at get_ctrl() is
> broken: if ptr_to_user() fails to fill a control due to an error,
> no errors are returned and v4l2_g_ctrl() returns success on a
> failed operation, which may cause applications to fail.
>
> Add an error check at get_ctrl() and ensure that it will
> be returned to userspace without filling the control value if
> get_ctrl() fails.
>
> Fixes: 71c689dc2e73 ("media: v4l2-ctrls: split up into four source files")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> ---
> drivers/media/v4l2-core/v4l2-ctrls-api.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-api.c b/drivers/media/v4l2-core/v4l2-ctrls-api.c
> index e5a364efd5e6..a0de7eeaf085 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls-api.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls-api.c
> @@ -753,9 +753,10 @@ static int get_ctrl(struct v4l2_ctrl *ctrl, struct v4l2_ext_control *c)
> for (i = 0; i < master->ncontrols; i++)
> cur_to_new(master->cluster[i]);
> ret = call_op(master, g_volatile_ctrl);
> - new_to_user(c, ctrl);
> + if (!ret)
> + ret = new_to_user(c, ctrl);
> } else {
> - cur_to_user(c, ctrl);
> + ret = cur_to_user(c, ctrl);
> }
> v4l2_ctrl_unlock(master);
> return ret;
> @@ -770,7 +771,10 @@ int v4l2_g_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_control *control)
> if (!ctrl || !ctrl->is_int)
> return -EINVAL;
> ret = get_ctrl(ctrl, &c);
> - control->value = c.value;
> +
> + if (!ret)
> + control->value = c.value;
> +
> return ret;
> }
> EXPORT_SYMBOL(v4l2_g_ctrl);
> @@ -811,10 +815,12 @@ static int set_ctrl_lock(struct v4l2_fh *fh, struct v4l2_ctrl *ctrl,
> int ret;
>
> v4l2_ctrl_lock(ctrl);
> - user_to_new(c, ctrl);
> + ret = user_to_new(c, ctrl);
> + if (ret)
> + return ret;
A lock was taken above and that isn't unlocked here.
It is better to write this as:
if (!ret)
ret = set_ctrl(fh, ctrl, 0);
> ret = set_ctrl(fh, ctrl, 0);
> if (!ret)
> - cur_to_user(c, ctrl);
> + ret = cur_to_user(c, ctrl);
> v4l2_ctrl_unlock(ctrl);
> return ret;
> }
Regards,
Hans
