On 16/10/2024 12:22, Mauro Carvalho Chehab wrote:

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@vger.kernel.org Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org

---

drivers/media/v4l2-core/v4l2-ctrls-api.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-ctrls-api.c b/drivers/media/v4l2-core/v4l2-ctrls-api.c index e5a364efd5e6..be32dccf9830 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);

Yeah, that's better.

There are also unchecked calls to cur_to_user() and user_to_new() in set_ctrl_lock().

Can you fix that as well?

Regards,

Hans