ipa: fix memory leak in ipa_s2n_get_list iteration

[alexey-tikhonov]

Per-step temporaries (retoid, retdata, parsed names, encoded requests) were allocated on the long-lived state context and never freed between iterations. Use a per-step talloc context and free retoid/retdata immediately after consumption.

Implementation assisted-by: Claude Code (Opus 4.6)

[gemini-code-assist]

Code Review

This pull request introduces a per-step memory context (step_ctx) to the ipa_s2n_get_list_state structure and updates several function calls to use this context, facilitating better memory management during iterations. Additionally, it ensures that override_attrs, retoid, and retdata are explicitly freed. The review feedback identifies a potential memory accumulation issue where state->attrs should also be freed at the start of each step to cover execution paths that bypass the standard cleanup.

[gemini-code-assist]

The state->attrs structure should also be freed at the beginning of each step. While it is currently freed in ipa_s2n_get_list_next, that function is only called during the Extended Operation (EXOP) path. If an iteration processes an IPA object (the ipa_id_get_account_info_send path), state->attrs from a previous EXOP iteration will remain in memory until the next EXOP iteration or until the entire request completes, leading to unnecessary memory accumulation.

    talloc_zfree(state->step_ctx);
    talloc_zfree(state->override_attrs);
    talloc_zfree(state->attrs);
    state->step_ctx = talloc_new(state);

[alexey-tikhonov]

Note: Covscan is clean.