[Nouveau] [PATCH AUTOSEL 5.4 04/25] drm/nouveau: clear output poll workers before nouveau_fbcon_destroy()

[Sasha Levin <sashal@kernel.org>]

From: Mark Menzynski <mmenzyns@redhat.com>

[ Upstream commit 6b03816f869529393b37d03e5d75b68f7365a7a4 ]

Resources needed for output poll workers are destroyed in
nouveau_fbcon_fini() before output poll workers are cleared in
nouveau_display_fini(). This means there is a time between fbcon_fini()
and display_fini(), where if output poll happens, it crashes.

This patch introduces another output poll clearing before fbcon
resources are destroyed.

BUG: KASAN: use-after-free in
__drm_fb_helper_initial_config_and_unlock.cold+0x1f3/0x291
[drm_kms_helper]

Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Mark Menzynski <mmenzyns@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220523113541.10562-1-mmenzyns@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/nouveau/nouveau_fbcon.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
index c09ea357e88f..325fc94791c6 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
@@ -39,6 +39,7 @@
 
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_probe_helper.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_atomic.h>
@@ -606,6 +607,7 @@ nouveau_fbcon_fini(struct drm_device *dev)
 	if (!drm->fbcon)
 		return;
 
+	drm_kms_helper_poll_fini(dev);
 	nouveau_fbcon_accel_fini(dev);
 	nouveau_fbcon_destroy(dev, drm->fbcon);
 	kfree(drm->fbcon);
-- 
2.35.1