From 598781d71119827b454fd75d46f84755bca6f0c6 Mon Sep 17 00:00:00 2001 From: Thomas Hellstrom Date: Tue, 24 Jan 2012 18:54:21 +0100 Subject: 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 Reviewed-by: Daniel Vetter Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_auth.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'drivers/gpu/drm/drm_auth.c') diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 3f46772f0cb..ba23790450e 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) -- cgit v1.2.3