The self-contained net_ncm fuzz harness #includes ncm_device.c and stubs
the usbd symbols it references rather than linking the device stack.
tud_network_link_state() now calls usbd_defer_func(), so add a matching
no-op stub to keep the harness linking.
folds the reproducer for the recv_validate_datagram bound into a small
self-contained fuzz target. it feeds a raw ntb straight into the validator
(the driver is pulled in so the static function is reachable) and ships the
crafted 64-byte ntb as a seed. the seed trips an asan heap-buffer-overflow
against the unpatched driver and is rejected cleanly with the wLength bound
in place.
Refactor event signal generation to limit bus signal events generated by fuzzing harnesses. The main point is that the issues listed by OSS-Fuzz does not seem to be true positives https://issues.oss-fuzz.com/issues?q=project%3Dtinyusb%20status%3Dnew
For example, the existing set up could generate USBD_EVENT_FUNC_CALL which is explicitly not a DCD event.
This fixes the harnesses so they don't run into several of the oss-fuzz open issues.
Currently OSS fuzz expects to have complete control over the
sanitizer flags. As we currently have these set it's causing
problems with the OSS fuzz build. Instead we should use the
provided variables from the OSS fuzz build environment. For
local testing we'll create a set a well defined defaults.
