From: Min Li <lm0963hack@gmail.com>
Date: Fri, 26 May 2023 13:01:31 +0000 (+0800)
Subject: drm/exynos: fix race condition UAF in exynos_g2d_exec_ioctl
X-Git-Tag: v6.1.37~43
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=022f2306d94f87defde366729938c5c54a3d12ff;p=platform%2Fkernel%2Flinux-starfive.git

drm/exynos: fix race condition UAF in exynos_g2d_exec_ioctl

[ Upstream commit 48bfd02569f5db49cc033f259e66d57aa6efc9a3 ]

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@gmail.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
index 471fd6c8135f..27613abeed96 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)
 		goto out;
 
 	wait_for_completion(&runqueue_node->complete);