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SubjectRe: [PATCH] drm: udl: Destroy framebuffer only if it was initialized
On Fri, Apr 20, 2018 at 01:50:01PM +0200, Emil Lundmark wrote:
> 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.
>

JFYI, in future, if someone makes a suggestion on how to fix a bug, it's good
practice to add a Suggested-by tag to give credit.

Reviewed-by: Sean Paul <seanpaul@chromium.org>

> Signed-off-by: Emil Lundmark <lndmrk@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
>

--
Sean Paul, Software Engineer, Google / Chromium OS

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