From 36e9d08b58f44c3a02974c405ccaaa6ecfaf05b8 Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Tue, 9 Aug 2016 02:16:18 +0200 Subject: [PATCH] drm/cirrus: Fix NULL pointer dereference when registering the fbdev cirrus_modeset_init() is initializing/registering the emulated fbdev and, since commit c61b93fe51b1 ("drm/atomic: Fix remaining places where !funcs->best_encoder is valid"), DRM internals can access/test some of the fields in mode_config->funcs as part of the fbdev registration process. Make sure dev->mode_config.funcs is properly set to avoid dereferencing a NULL pointer. Reported-by: Mike Marshall Reported-by: Eric W. Biederman Signed-off-by: Boris Brezillon Fixes: c61b93fe51b1 ("drm/atomic: Fix remaining places where !funcs->best_encoder is valid") Signed-off-by: Dave Airlie --- drivers/gpu/drm/cirrus/cirrus_main.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/cirrus/cirrus_main.c b/drivers/gpu/drm/cirrus/cirrus_main.c index 80446e2d3ab6e..76bcb43e7c06a 100644 --- a/drivers/gpu/drm/cirrus/cirrus_main.c +++ b/drivers/gpu/drm/cirrus/cirrus_main.c @@ -185,14 +185,23 @@ int cirrus_driver_load(struct drm_device *dev, unsigned long flags) goto out; } + /* + * cirrus_modeset_init() is initializing/registering the emulated fbdev + * and DRM internals can access/test some of the fields in + * mode_config->funcs as part of the fbdev registration process. + * Make sure dev->mode_config.funcs is properly set to avoid + * dereferencing a NULL pointer. + * FIXME: mode_config.funcs assignment should probably be done in + * cirrus_modeset_init() (that's a common pattern seen in other DRM + * drivers). + */ + dev->mode_config.funcs = &cirrus_mode_funcs; r = cirrus_modeset_init(cdev); if (r) { dev_err(&dev->pdev->dev, "Fatal error during modeset init: %d\n", r); goto out; } - dev->mode_config.funcs = (void *)&cirrus_mode_funcs; - return 0; out: cirrus_driver_unload(dev); -- 2.39.5