llvmpipe: segfault when trying to render to imported prime buffer
The llvmpipe EGL interface allows importing prime buffers from other DRM devices. When trying to render to them, llvmpipe uses DRM_IOCTL_MODE_MAP_DUMB to map them. This will always fail but llvmpipe does not check the return value for NULL and will then segfault when trying to dereference the pointer.
llvmpipe should either support mapping arbitrary imported buffers (maybe via GBM) or it should reject such images at import time.