From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933637AbbLXPoS (ORCPT ); Thu, 24 Dec 2015 10:44:18 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51525 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754225AbbLXPme (ORCPT ); Thu, 24 Dec 2015 10:42:34 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Thomas Hellstrom" , "Dave Airlie" Date: Thu, 24 Dec 2015 15:37:42 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 46/77] drm: Fix an unwanted master inheritance v2 In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.247 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.75-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Hellstrom commit a0af2e538c80f3e47f1d6ddf120a153ad909e8ad upstream. A client calling drmSetMaster() using a file descriptor that was opened when another client was master would inherit the latter client's master object and all its authenticated clients. This is unwanted behaviour, and when this happens, instead allocate a brand new master object for the client calling drmSetMaster(). Fixes a BUG() throw in vmw_master_set(). Signed-off-by: Thomas Hellstrom Signed-off-by: Dave Airlie [bwh: Backported to 3.2: - s/master_mutex/struct_mutex/ - drm_new_set_master() must drop struct_mutex while calling drm_driver::master_create - Adjust filename, context, indentation] Signed-off-by: Ben Hutchings --- --- a/drivers/gpu/drm/drm_stub.c +++ b/drivers/gpu/drm/drm_stub.c @@ -225,6 +225,10 @@ int drm_setmaster_ioctl(struct drm_devic if (!file_priv->minor->master && file_priv->minor->master != file_priv->master) { mutex_lock(&dev->struct_mutex); + if (!file_priv->allowed_master) { + ret = drm_new_set_master(dev, file_priv); + goto out_unlock; + } file_priv->minor->master = drm_master_get(file_priv->master); file_priv->is_master = 1; if (dev->driver->master_set) { @@ -234,10 +238,11 @@ int drm_setmaster_ioctl(struct drm_devic drm_master_put(&file_priv->minor->master); } } + out_unlock: mutex_unlock(&dev->struct_mutex); } - return 0; + return ret; } int drm_dropmaster_ioctl(struct drm_device *dev, void *data, --- a/drivers/gpu/drm/drm_fops.c +++ b/drivers/gpu/drm/drm_fops.c @@ -219,6 +219,62 @@ static int drm_cpu_valid(void) } /** + * drm_new_set_master - Allocate a new master object and become master for the + * associated master realm. + * + * @dev: The associated device. + * @fpriv: File private identifying the client. + * + * This function must be called with dev::struct_mutex held. + * Returns negative error code on failure. Zero on success. + */ +int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv) +{ + struct drm_master *old_master; + int ret; + + lockdep_assert_held_once(&dev->struct_mutex); + + /* create a new master */ + fpriv->minor->master = drm_master_create(fpriv->minor); + if (!fpriv->minor->master) + return -ENOMEM; + + /* take another reference for the copy in the local file priv */ + old_master = fpriv->master; + fpriv->master = drm_master_get(fpriv->minor->master); + + if (dev->driver->master_create) { + mutex_unlock(&dev->struct_mutex); + ret = dev->driver->master_create(dev, fpriv->master); + mutex_lock(&dev->struct_mutex); + if (ret) + goto out_err; + } + if (dev->driver->master_set) { + ret = dev->driver->master_set(dev, fpriv, true); + if (ret) + goto out_err; + } + + fpriv->is_master = 1; + fpriv->allowed_master = 1; + fpriv->authenticated = 1; + if (old_master) + drm_master_put(&old_master); + + return 0; + +out_err: + /* drop both references and restore old master on failure */ + drm_master_put(&fpriv->minor->master); + drm_master_put(&fpriv->master); + fpriv->master = old_master; + + return ret; +} + +/** * Called whenever a process opens /dev/drm. * * \param inode device inode. @@ -279,43 +335,10 @@ static int drm_open_helper(struct inode mutex_lock(&dev->struct_mutex); if (!priv->minor->master) { /* create a new master */ - priv->minor->master = drm_master_create(priv->minor); - if (!priv->minor->master) { - mutex_unlock(&dev->struct_mutex); - ret = -ENOMEM; - goto out_free; - } - - priv->is_master = 1; - /* take another reference for the copy in the local file priv */ - priv->master = drm_master_get(priv->minor->master); - - priv->authenticated = 1; - - mutex_unlock(&dev->struct_mutex); - if (dev->driver->master_create) { - ret = dev->driver->master_create(dev, priv->master); - if (ret) { - mutex_lock(&dev->struct_mutex); - /* drop both references if this fails */ - drm_master_put(&priv->minor->master); - drm_master_put(&priv->master); - mutex_unlock(&dev->struct_mutex); - goto out_free; - } - } - mutex_lock(&dev->struct_mutex); - if (dev->driver->master_set) { - ret = dev->driver->master_set(dev, priv, true); - if (ret) { - /* drop both references if this fails */ - drm_master_put(&priv->minor->master); - drm_master_put(&priv->master); - mutex_unlock(&dev->struct_mutex); - goto out_free; - } - } + ret = drm_new_set_master(dev, priv); mutex_unlock(&dev->struct_mutex); + if (ret) + goto out_free; } else { /* get a reference to the master */ priv->master = drm_master_get(priv->minor->master); --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -430,6 +430,11 @@ struct drm_file { void *driver_priv; int is_master; /* this file private is a master for a minor */ + /* + * This client is allowed to gain master privileges for @master. + * Protected by struct drm_device::struct_mutex. + */ + unsigned allowed_master:1; struct drm_master *master; /* master this node is currently associated with N.B. not always minor->master */ struct list_head fbs; @@ -1254,6 +1259,7 @@ extern int drm_fasync(int fd, struct fil extern ssize_t drm_read(struct file *filp, char __user *buffer, size_t count, loff_t *offset); extern int drm_release(struct inode *inode, struct file *filp); +extern int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv); /* Mapping support (drm_vm.h) */ extern int drm_mmap(struct file *filp, struct vm_area_struct *vma);