[PATCH] drm/vmwgfx: NULL pointer dereference from vmw_cmd_dx_view_define()

[Murray McAllister]

If SVGA_3D_CMD_DX_DEFINE_RENDERTARGET_VIEW is called with a surface
ID of SVGA3D_INVALID_ID, the srf struct will remain NULL after
vmw_cmd_res_check(), leading to a null pointer dereference in
vmw_view_add().

Signed-off-by: Murray McAllister <murray.mcallister at gmail.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index 2ff7ba04d8c8..447afd086206 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -2414,6 +2414,10 @@ static int vmw_cmd_dx_view_define(struct vmw_private *dev_priv,
 		return -EINVAL;
 
 	cmd = container_of(header, typeof(*cmd), header);
+	if (unlikely(cmd->sid == SVGA3D_INVALID_ID)) {
+		DRM_ERROR("Invalid surface id.\n");
+		return -EINVAL;
+	}
 	ret = vmw_cmd_res_check(dev_priv, sw_context, vmw_res_surface,
 				VMW_RES_DIRTY_NONE, user_surface_converter,
 				&cmd->sid, &srf);
-- 
2.20.1