diff options
| author | Thomas Hellstrom <thellstrom@vmware.com> | 2012-01-24 18:54:21 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-02-03 09:18:52 -0800 |
| commit | 90af660bec3b2d47e17cb3caae742810656e2d4f (patch) | |
| tree | e8f4d93c7386c19dd9b50156696b4447ba7877d6 /drivers | |
| parent | c196878589eb5f88e244a557a55b229a3c285b3b (diff) | |
drm: Fix authentication kernel crash
commit 598781d71119827b454fd75d46f84755bca6f0c6 upstream.
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>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/drm_auth.c | 6 | ||||
| -rw-r--r-- | drivers/gpu/drm/drm_fops.c | 5 |
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 2ec7d48fc4a8..c42e12cc2ddb 100644 --- a/drivers/gpu/drm/drm_fops.c +++ b/drivers/gpu/drm/drm_fops.c @@ -486,6 +486,11 @@ 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); |