[Intel-gfx] [PATCH] 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: GMINL-7446
Change-Id: I901ff713be53c5ec1c9eaf7ee0ff4314a659af05
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 f645268..80253a7 100644
--- a/drivers/gpu/drm/drm_lock.c
+++ b/drivers/gpu/drm/drm_lock.c
@@ -156,6 +156,14 @@ int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
 		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 -EINTR;
+	}
+
 	if (drm_lock_free(&master->lock, lock->context)) {
 		/* FIXME: Should really bail out here. */
 	}
-- 
1.9.1

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