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authorThomas Hellstrom <thellstrom@vmware.com>2012-01-24 18:54:21 +0100
committerDave Airlie <airlied@redhat.com>2012-01-25 09:27:45 +0000
commit598781d71119827b454fd75d46f84755bca6f0c6 (patch)
tree51ccb65b8e26b3347099af3f466ad0fedc6e1cb6 /drivers
parent15b63d35261ba3351d07e7937252f18bb6cbf814 (diff)
downloadlinux-linaro-stable-598781d71119827b454fd75d46f84755bca6f0c6.tar.gz
drm: Fix authentication kernel crash
If the master tries to authenticate a client using drm_authmagic and that client has already closed its drm file descriptor, either wilfully or because it was terminated, the call to drm_authmagic will dereference a stale pointer into kmalloc'ed memory and corrupt it. Typically this results in a hard system hang. This patch fixes that problem by removing any authentication tokens (struct drm_magic_entry) open for a file descriptor when that file descriptor is closed. Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/gpu/drm/drm_auth.c6
-rw-r--r--drivers/gpu/drm/drm_fops.c5
2 files changed, 10 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index 3f46772f0cb2..ba23790450e9 100644
--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c
@@ -101,7 +101,7 @@ static int drm_add_magic(struct drm_master *master, struct drm_file *priv,
* Searches and unlinks the entry in drm_device::magiclist with the magic
* number hash key, while holding the drm_device::struct_mutex lock.
*/
-static int drm_remove_magic(struct drm_master *master, drm_magic_t magic)
+int drm_remove_magic(struct drm_master *master, drm_magic_t magic)
{
struct drm_magic_entry *pt;
struct drm_hash_item *hash;
@@ -136,6 +136,8 @@ static int drm_remove_magic(struct drm_master *master, drm_magic_t magic)
* If there is a magic number in drm_file::magic then use it, otherwise
* searches an unique non-zero magic number and add it associating it with \p
* file_priv.
+ * This ioctl needs protection by the drm_global_mutex, which protects
+ * struct drm_file::magic and struct drm_magic_entry::priv.
*/
int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
@@ -173,6 +175,8 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
* \return zero if authentication successed, or a negative number otherwise.
*
* Checks if \p file_priv is associated with the magic number passed in \arg.
+ * This ioctl needs protection by the drm_global_mutex, which protects
+ * struct drm_file::magic and struct drm_magic_entry::priv.
*/
int drm_authmagic(struct drm_device *dev, void *data,
struct drm_file *file_priv)
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index c00cf154cc0b..6263b0147598 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -487,6 +487,11 @@ int drm_release(struct inode *inode, struct file *filp)
(long)old_encode_dev(file_priv->minor->device),
dev->open_count);
+ /* Release any auth tokens that might point to this file_priv,
+ (do that under the drm_global_mutex) */
+ if (file_priv->magic)
+ (void) drm_remove_magic(file_priv->master, file_priv->magic);
+
/* if the master has gone away we can't do anything with the lock */
if (file_priv->minor->master)
drm_master_release(dev, filp);