From 7cfc4ea78fc103ea51ecbacd9236abb5b1c490d2 Mon Sep 17 00:00:00 2001

From: Neil Armstrong <narmstrong@baylibre.com>

Date: Fri, 30 Apr 2021 10:27:44 +0200

Subject: [PATCH] drm/meson: fix shutdown crash when component not probed

Git-commit: 7cfc4ea78fc103ea51ecbacd9236abb5b1c490d2

Patch-mainline: v5.13-rc4

References: git-fixes

When main component is not probed, by example when the dw-hdmi module is

not loaded yet or in probe defer, the following crash appears on shutdown:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000038

...

pc : meson_drv_shutdown+0x24/0x50

lr : platform_drv_shutdown+0x20/0x30

...

Call trace:

meson_drv_shutdown+0x24/0x50

platform_drv_shutdown+0x20/0x30

device_shutdown+0x158/0x360

kernel_restart_prepare+0x38/0x48

kernel_restart+0x18/0x68

__do_sys_reboot+0x224/0x250

__arm64_sys_reboot+0x24/0x30

...

Simply check if the priv struct has been allocated before using it.

Fixes: fa0c16caf3d7 ("drm: meson_drv add shutdown function")

Reported-by: Stefan Agner <stefan@agner.ch>

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Link: https://patchwork.freedesktop.org/patch/msgid/20210430082744.3638743-1-narmstrong@baylibre.com

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/gpu/drm/meson/meson_drv.c | 9 +++++----

 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c

index 453d8b4c5763..07fcd12dca16 100644

--- a/drivers/gpu/drm/meson/meson_drv.c

+++ b/drivers/gpu/drm/meson/meson_drv.c

@@ -485,11 +485,12 @@ static int meson_probe_remote(struct platform_device *pdev,

 static void meson_drv_shutdown(struct platform_device *pdev)

 {

 	struct meson_drm *priv = dev_get_drvdata(&pdev->dev);

-	struct drm_device *drm = priv->drm;

-	DRM_DEBUG_DRIVER("\n");

-	drm_kms_helper_poll_fini(drm);

-	drm_atomic_helper_shutdown(drm);

+	if (!priv)

+		return;

+

+	drm_kms_helper_poll_fini(priv->drm);

+	drm_atomic_helper_shutdown(priv->drm);

 }

 static int meson_drv_probe(struct platform_device *pdev)

-- 

2.26.2