[PATCH] drm: udl: Destroy framebuffer only if it was initialized

Emil Lundmark lndmrk at chromium.org
Fri Apr 20 11:50:01 UTC 2018


This fixes a NULL pointer dereference that can happen if the UDL
driver is unloaded before the framebuffer is initialized. This can
happen e.g. if the USB device is unplugged right after it was plugged
in.

Signed-off-by: Emil Lundmark <lndmrk at chromium.org>
---
 drivers/gpu/drm/udl/udl_fb.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
index 2ebdc6d5a76e..5754e37f741b 100644
--- a/drivers/gpu/drm/udl/udl_fb.c
+++ b/drivers/gpu/drm/udl/udl_fb.c
@@ -426,9 +426,11 @@ static void udl_fbdev_destroy(struct drm_device *dev,
 {
 	drm_fb_helper_unregister_fbi(&ufbdev->helper);
 	drm_fb_helper_fini(&ufbdev->helper);
-	drm_framebuffer_unregister_private(&ufbdev->ufb.base);
-	drm_framebuffer_cleanup(&ufbdev->ufb.base);
-	drm_gem_object_put_unlocked(&ufbdev->ufb.obj->base);
+	if (ufbdev->ufb.obj) {
+		drm_framebuffer_unregister_private(&ufbdev->ufb.base);
+		drm_framebuffer_cleanup(&ufbdev->ufb.base);
+		drm_gem_object_put_unlocked(&ufbdev->ufb.obj->base);
+	}
 }
 
 int udl_fbdev_init(struct drm_device *dev)
-- 
2.17.0.484.g0c8726318c-goog



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