FreeBSD: VID-c1b2b492-6999-11ec-a50c-001cc0382b2f (CVE-2021-44732): Mbed TLS -- Potential double-free after an out of memory error

Manuel Pégourié-Gonnard reports: If mbedtls_ssl_set_session() or mbedtls_ssl_get_session() were to fail with MBEDTLS_ERR_SSL_ALLOC_FAILED (in an out of memory condition), then calling mbedtls_ssl_session_free() and mbedtls_ssl_free() in the usual manner would cause an internal session buffer to be freed twice, due to two structures both having valid pointers to it after a call to ssl_session_copy(). An attacker could potentially trigger the out of memory condition, and therefore use this bug to create memory corruption, which could then be further exploited or targetted.