[PATCH 4.19 57/75] drm/vmwgfx: integer underflow in vmw_cmd_dx_set_shader() leading to an invalid read

[Greg Kroah-Hartman]

From: Murray McAllister <murray.mcallister@xxxxxxxxx>

commit 5ed7f4b5eca11c3c69e7c8b53e4321812bc1ee1e upstream.

If SVGA_3D_CMD_DX_SET_SHADER is called with a shader ID
of SVGA3D_INVALID_ID, and a shader type of
SVGA3D_SHADERTYPE_INVALID, the calculated binding.shader_slot
will be 4294967295, leading to an out-of-bounds read in vmw_binding_loc()
when the offset is calculated.

Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: d80efd5cb3de ("drm/vmwgfx: Initial DX support")
Signed-off-by: Murray McAllister <murray.mcallister@xxxxxxxxx>
Reviewed-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>


---
 drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -2493,7 +2493,8 @@ static int vmw_cmd_dx_set_shader(struct
 
 	cmd = container_of(header, typeof(*cmd), header);
 
-	if (cmd->body.type >= SVGA3D_SHADERTYPE_DX10_MAX) {
+	if (cmd->body.type >= SVGA3D_SHADERTYPE_DX10_MAX ||
+	    cmd->body.type < SVGA3D_SHADERTYPE_MIN) {
 		DRM_ERROR("Illegal shader type %u.\n",
 			  (unsigned) cmd->body.type);
 		return -EINVAL;