[PATCH 5.12 117/296] drm/meson: fix shutdown crash when component not probed

Greg Kroah-Hartman
2021-05-31T16:17:20Z

From: Neil Armstrong <narmstrong@baylibre.com>

commit 7cfc4ea78fc103ea51ecbacd9236abb5b1c490d2 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/meson/meson_drv.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

--- 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 pla
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)