[PATCH] drm/radeon: check bo_va->bo is non-NULL before using it

[Pierre-Eric Pelloux-Prayer]

The call to radeon_vm_clear_freed might clear bo_va->bo, so
we have to check it before dereferencing it.

Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
---
 drivers/gpu/drm/radeon/radeon_gem.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index 3fec3acdaf28..0cf1a72091b7 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -641,8 +641,17 @@ static void radeon_gem_va_update_vm(struct radeon_device *rdev,
 	if (r)
 		goto error_unlock;
 
-	if (bo_va->it.start)
+	if (bo_va->it.start) {
+		if (bo_va->bo == NULL) {
+			/* Buggy userspace can try to use RADEON_VA_UNMAP after
+			 * closing the BO. In this case, radeon_vm_clear_freed
+			 * will unset bo_va->bo.
+			 */
+			r = -ENOENT;
+			goto error_unlock;
+		}
 		r = radeon_vm_bo_update(rdev, bo_va, bo_va->bo->tbo.resource);
+	}
 
 error_unlock:
 	mutex_unlock(&bo_va->vm->mutex);
-- 
2.45.2