linux-kernel - [PATCH v3] drm/nouveau: clear output poll workers before nouveau_fbcon

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Message-Id: <20220523113541.10562-1-mmenzyns@redhat.com>
Date:   Mon, 23 May 2022 13:35:41 +0200
From:   Mark Menzynski <mmenzyns@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Mark Menzynski <mmenzyns@...hat.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Karol Herbst <kherbst@...hat.com>,
        Lyude Paul <lyude@...hat.com>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org
Subject: [PATCH v3] drm/nouveau: clear output poll workers before nouveau_fbcon_destroy()

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@...hat.com>
Cc: Karol Herbst <kherbst@...hat.com>
Cc: Lyude Paul <lyude@...hat.com>
Cc: David Airlie <airlied@...ux.ie>
Cc: Daniel Vetter <daniel@...ll.ch>
Cc: dri-devel@...ts.freedesktop.org
Cc: nouveau@...ts.freedesktop.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Mark Menzynski <mmenzyns@...hat.com>
---
 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 4f9b3aa5deda..5226323e55d3 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>
@@ -605,6 +606,7 @@ 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);
-- 
2.32.0