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authorBoris Brezillon <boris.brezillon@free-electrons.com>2016-08-09 02:16:18 +0200
committerDave Airlie <airlied@redhat.com>2016-08-09 13:01:47 +1000
commit36e9d08b58f44c3a02974c405ccaaa6ecfaf05b8 (patch)
tree02e9bc0c84ac36db3b49c8be2620dc949f4195ad
parent210a021dab639694600450c14b877bf3e3240adc (diff)
drm/cirrus: Fix NULL pointer dereference when registering the fbdevdrm-fixes-for-4.8-rc2
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 <hubcap@omnibond.com> Reported-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Fixes: c61b93fe51b1 ("drm/atomic: Fix remaining places where !funcs->best_encoder is valid") Signed-off-by: Dave Airlie <airlied@redhat.com>
-rw-r--r--drivers/gpu/drm/cirrus/cirrus_main.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/gpu/drm/cirrus/cirrus_main.c b/drivers/gpu/drm/cirrus/cirrus_main.c
index 80446e2d3ab6..76bcb43e7c06 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);