[PATCH] drm/fb_dma: Add checks in drm_fb_dma_get_scanout_buffer()

[Jocelyn Falempe]

plane->state and plane->state->fb can be NULL, so add a check before
dereferencing them.
Found by testing with the imx driver.

Fixes: 879b3b6511fe9 ("drm/fb_dma: Add generic get_scanout_buffer() for 
drm_panic")
Signed-off-by: Jocelyn Falempe <jfale...@redhat.com>
---
 drivers/gpu/drm/drm_fb_dma_helper.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_fb_dma_helper.c 
b/drivers/gpu/drm/drm_fb_dma_helper.c
index 96e5ab960f12..d7bffde94cc5 100644
--- a/drivers/gpu/drm/drm_fb_dma_helper.c
+++ b/drivers/gpu/drm/drm_fb_dma_helper.c
@@ -167,6 +167,9 @@ int drm_fb_dma_get_scanout_buffer(struct drm_plane *plane,
        struct drm_gem_dma_object *dma_obj;
        struct drm_framebuffer *fb;
 
+       if (!plane->state || !plane->state->fb)
+               return -ENODEV;
+
        fb = plane->state->fb;
        /* Only support linear modifier */
        if (fb->modifier != DRM_FORMAT_MOD_LINEAR)

base-commit: 2e3f08a1ac99cb9a19a5cb151593d4f9df5cc6a7
-- 
2.44.0