drm/vmwgfx: integer underflow in vmw_cmd_dx_set_shader() leading to an invalid read

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@vger.kernel.org>
Fixes: d80efd5cb3de ("drm/vmwgfx: Initial DX support")
Signed-off-by: Murray McAllister <murray.mcallister@gmail.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index b4c7553..33533d1 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -2206,7 +2206,8 @@ static int vmw_cmd_dx_set_shader(struct vmw_private *dev_priv,
 
        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) {
                VMW_DEBUG_USER("Illegal shader type %u.\n",
                               (unsigned int) cmd->body.type);
                return -EINVAL;