From c996fd0b956450563454e7ccc97a82ca31f9d043 Mon Sep 17 00:00:00 2001 From: Thomas Hellstrom Date: Tue, 25 Feb 2014 19:57:44 +0100 Subject: drm: Protect the master management with a drm_device::master_mutex v3 The master management was previously protected by the drm_device::struct_mutex. In order to avoid locking order violations in a reworked dropped master security check in the vmwgfx driver, break it out into a separate master_mutex. Locking order is master_mutex -> struct_mutex. Also remove drm_master::blocked since it's not used. v2: Add an inline comment about what drm_device::master_mutex is protecting. v3: Remove unneeded struct_mutex locks. Fix error returns in drm_setmaster_ioctl(). Signed-off-by: Thomas Hellstrom Reviewed-by: Brian Paul Reviewed-by: David Herrmann Acked-by: Daniel Vetter --- drivers/gpu/drm/drm_stub.c | 43 ++++++++++++++++++++++++++++--------------- 1 file changed, 28 insertions(+), 15 deletions(-) (limited to 'drivers/gpu/drm/drm_stub.c') diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c index a378af49ed2e..fac6f9834257 100644 --- a/drivers/gpu/drm/drm_stub.c +++ b/drivers/gpu/drm/drm_stub.c @@ -144,6 +144,7 @@ static void drm_master_destroy(struct kref *kref) struct drm_device *dev = master->minor->dev; struct drm_map_list *r_list, *list_temp; + mutex_lock(&dev->struct_mutex); if (dev->driver->master_destroy) dev->driver->master_destroy(dev, master); @@ -171,6 +172,7 @@ static void drm_master_destroy(struct kref *kref) drm_ht_remove(&master->magiclist); + mutex_unlock(&dev->struct_mutex); kfree(master); } @@ -186,19 +188,20 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data, { int ret = 0; + mutex_lock(&dev->master_mutex); if (file_priv->is_master) - return 0; + goto out_unlock; - if (file_priv->minor->master && file_priv->minor->master != file_priv->master) - return -EINVAL; - - if (!file_priv->master) - return -EINVAL; + if (file_priv->minor->master) { + ret = -EINVAL; + goto out_unlock; + } - if (file_priv->minor->master) - return -EINVAL; + if (!file_priv->master) { + ret = -EINVAL; + goto out_unlock; + } - mutex_lock(&dev->struct_mutex); file_priv->minor->master = drm_master_get(file_priv->master); file_priv->is_master = 1; if (dev->driver->master_set) { @@ -208,27 +211,33 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data, drm_master_put(&file_priv->minor->master); } } - mutex_unlock(&dev->struct_mutex); +out_unlock: + mutex_unlock(&dev->master_mutex); return ret; } int drm_dropmaster_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv) { + int ret = -EINVAL; + + mutex_lock(&dev->master_mutex); if (!file_priv->is_master) - return -EINVAL; + goto out_unlock; if (!file_priv->minor->master) - return -EINVAL; + goto out_unlock; - mutex_lock(&dev->struct_mutex); + ret = 0; if (dev->driver->master_drop) dev->driver->master_drop(dev, file_priv, false); drm_master_put(&file_priv->minor->master); file_priv->is_master = 0; - mutex_unlock(&dev->struct_mutex); - return 0; + +out_unlock: + mutex_unlock(&dev->master_mutex); + return ret; } /* @@ -559,6 +568,7 @@ struct drm_device *drm_dev_alloc(struct drm_driver *driver, spin_lock_init(&dev->event_lock); mutex_init(&dev->struct_mutex); mutex_init(&dev->ctxlist_mutex); + mutex_init(&dev->master_mutex); dev->anon_inode = drm_fs_inode_new(); if (IS_ERR(dev->anon_inode)) { @@ -612,6 +622,7 @@ err_minors: drm_minor_free(dev, DRM_MINOR_CONTROL); drm_fs_inode_free(dev->anon_inode); err_free: + mutex_destroy(&dev->master_mutex); kfree(dev); return NULL; } @@ -633,6 +644,8 @@ static void drm_dev_release(struct kref *ref) drm_minor_free(dev, DRM_MINOR_CONTROL); kfree(dev->devname); + + mutex_destroy(&dev->master_mutex); kfree(dev); } -- cgit