When a virtio-gpu resource is destroyed, any associated udmabuf must be
properly torn down. Currently, the code may leave dangling references
to dmabuf file descriptors in the scanout primary buffers.
This patch updates virtio_gpu_fini_udmabuf to:
1. Iterate through all active scanouts.
2. Identify dmabufs that match the resource's file descriptor.
3. Close the dmabuf and invalidate the resource's FD reference to
prevent use-after-free or double-close scenarios.
4. Finally, trigger the underlying udmabuf destruction.
This ensures that the display backend does not attempt to access
memory or FDs that have been released by the guest or the host.
Cc: Alex Bennée <alex.bennee@linaro.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
Message-ID: <20260304203230.1955266-1-dongwon.kim@intel.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
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