NvHost Syncpoint Security Configuration

The NvHost architecture guarantees that only the syncpoint owner can release a syncpoint, ensuring signal authenticity for other processes waiting on that syncpoint.

The explicit_syncpt_free parameter (enabled by default) enforces this policy by requiring an explicit free before a syncpoint returns to the free pool. When disabled, syncpoints may also be released automatically if the owner process terminates ungracefully. The waiter may continue waiting on a syncpoint that has been reallocated to a different process without being aware that the signaler identity has changed.

If a client overrides the default behavior by disabling explicit_syncpt_free, NvHost can no longer guarantee signaler authenticity.

Parameter Configuration

explicit_syncpt_free is a module parameter for the tegra-drm kernel module.

• explicit_syncpt_free=1 (default): Enforces strict ownership; only the owning process may release a syncpoint.

• explicit_syncpt_free=0: Disables strict ownership enforcement and allows the syncpoint to be released automatically if the owner process terminates ungracefully.

Set the parameter in /etc/modprobe.d/tegra-drm.conf:

options tegra-drm explicit_syncpt_free=0