[PATCH 1/5] drm: Kernel Crash in drm_unlock

[Peter Antoine]

This patch fixes a possible kernel crash when drm_unlock (DRM_IOCTL_UNLOCK)
is called by a application that has not had a lock created by it. This
crash can be caused by any application from all users.

Issue: VIZ-5485
Signed-off-by: Peter Antoine <peter.antoine at intel.com>
---
 drivers/gpu/drm/drm_lock.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/drm_lock.c b/drivers/gpu/drm/drm_lock.c
index f861361..070dd5d 100644
--- a/drivers/gpu/drm/drm_lock.c
+++ b/drivers/gpu/drm/drm_lock.c
@@ -159,6 +159,14 @@ int drm_legacy_unlock(struct drm_device *dev, void *data, struct drm_file *file_
 		return -EINVAL;
 	}
 
+	if (!master->lock.hw_lock) {
+		DRM_ERROR(
+			"Device has been unregistered. Hard exit. Process %d\n",
+			task_pid_nr(current));
+		send_sig(SIGTERM, current, 0);
+		return -EPERM;
+	}
+
 	if (drm_legacy_lock_free(&master->lock, lock->context)) {
 		/* FIXME: Should really bail out here. */
 	}
-- 
1.9.1