Summary
In php_stream_url_wrap_http_ex, when TLS crypto setup fails (via php_stream_xport_crypto_setup or php_stream_xport_crypto_enable), the stream is closed and reset to NULL.
However, the subsequent peer name cleanup block unconditionally tries to reset the peer name.
This is triggerable via a failure to validate the peer name or an expired certificate.
As demonstrated by https://github.com/php/php-src/issues/21468 this is triggerable without requiring specially-crafted code, and with a remote server.
Details
Patch available via https://github.com/php/php-src/pull/21031
Impact
The impact is a remotely-triggerable DoS bringing the entire fpm process down with all its workers.
Additional Information
This was first discovered by a hybrid static-dynamic analyzer I'm developing.