From: Emil Lundmark Date: Mon, 28 May 2018 14:27:11 +0000 (+0200) Subject: drm: udl: Destroy framebuffer only if it was initialized X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=5575041b09cd00e5dca79f8c6006edfb3012ab25;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git drm: udl: Destroy framebuffer only if it was initialized commit fcb74da1eb8edd3a4ef9b9724f88ed709d684227 upstream. 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. As explained by Stéphane Marchesin: It happens when fbdev is disabled (which is the case for Chrome OS). Even though intialization of the fbdev part is optional (it's done in udlfb_create which is the callback for fb_probe()), the teardown isn't optional (udl_driver_unload -> udl_fbdev_cleanup -> udl_fbdev_destroy). Note that udl_fbdev_cleanup *tries* to be conditional (you can see it does if (!udl->fbdev)) but that doesn't work, because udl->fbdev is always set during udl_fbdev_init. Cc: stable@vger.kernel.org Suggested-by: Sean Paul Reviewed-by: Sean Paul Acked-by: Daniel Vetter Signed-off-by: Emil Lundmark Signed-off-by: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20180528142711.142466-1-lndmrk@chromium.org Signed-off-by: Sean Paul Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c index 8746eeeec44d..491f1892b50e 100644 --- a/drivers/gpu/drm/udl/udl_fb.c +++ b/drivers/gpu/drm/udl/udl_fb.c @@ -432,9 +432,11 @@ 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)