Hi Andi, On Wed, May 31, 2023 at 6:21 AM Andi Shyti <andi.shyti@xxxxxxxxxx> wrote: > > Hi Min, > > On Fri, May 26, 2023 at 09:01:31PM +0800, Min Li wrote: > > If it is async, runqueue_node is freed in g2d_runqueue_worker on another > > worker thread. So in extreme cases, if g2d_runqueue_worker runs first, and > > then executes the following if statement, there will be use-after-free. > > > > Signed-off-by: Min Li <lm0963hack@xxxxxxxxx> > > --- > > drivers/gpu/drm/exynos/exynos_drm_g2d.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c > > index ec784e58da5c..414e585ec7dd 100644 > > --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c > > +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c > > @@ -1335,7 +1335,7 @@ int exynos_g2d_exec_ioctl(struct drm_device *drm_dev, void *data, > > /* Let the runqueue know that there is work to do. */ > > queue_work(g2d->g2d_workq, &g2d->runqueue_work); > > > > - if (runqueue_node->async) > > + if (req->async) > > did you actually hit this? If you did, then the fix is not OK. No, I didn't actually hit this. I found it through code review. This is only a theoretical issue that can only be triggered in extreme cases. > > Andi > > > goto out; > > > > wait_for_completion(&runqueue_node->complete); > > -- > > 2.34.1 > > -- Min Li
