devdanzin/socket_audit_leaks.md

Created March 18, 2026 10:07

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socketmodule.c: Reference and buffer leaks via audit hook failures

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socket_audit_leaks.md

socketmodule.c: Reference and buffer leaks via audit hook failures

Summary

Two leak bugs in socketmodule.c triggered when PySys_Audit raises:

getaddrinfo (line 6983): idna and/or pstr refs leaked when audit hook raises. ~657 objects leaked per 1000 calls.
sock_sendto (line 4810): pbuf Py_buffer not released when audit hook raises.

Reproducer (getaddrinfo leak)

import socket, sys

sys.addaudithook(lambda *a: (_ for _ in ()).throw(RuntimeError("audit")))
before = sys.gettotalrefcount()
for i in range(1000):
    try:
        socket.getaddrinfo("localhost", 80)
    except RuntimeError:
        pass
after = sys.gettotalrefcount()
print(f"Leaked {after - before} objects in 1000 calls")

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