isisd: clear route-map reference on redistribute unset

[Evelyn0828]

Release the route-map reference when an IS-IS redistribution entry is removed or when the area is torn down. This keeps show route-map unused consistent after the redistribution command is removed.

CLOSES #22361

[greptile-apps]

Greptile Summary

This PR fixes two related resource-management bugs in isisd/isis_redist.c: a memory leak of the map_name string and a missing route_map_counter_decrement call, both triggered when a redistribution entry is removed or an area is torn down.

• isis_redist_unset: adds isis_redist_routemap_set(redist, NULL) before the struct is freed, which correctly frees map_name and decrements the route-map use counter (both were silently skipped in the original code).
• isis_redist_area_finish: replaces the bare XFREE(MTYPE_ISIS_RMAP_NAME, redist->map_name) with isis_redist_routemap_set(redist, NULL), adding the missing counter decrement so show route-map unused reports correctly after area teardown.

Confidence Score: 5/5

Safe to merge — the change is a targeted cleanup of two resource-management paths with no behavioral changes to route advertisement logic.

Both hunks replace either a missing cleanup or an incomplete one with the existing isis_redist_routemap_set(redist, NULL) helper, which already handles the NULL case as a no-op. The struct is still freed after the helper returns, so there is no use-after-free. The area-finish loop uses ALL_LIST_ELEMENTS (safe for in-loop deletion). No new logic is introduced and the change is consistent with how the same helper is used elsewhere in the file.

No files require special attention.

Important Files Changed

Filename	Overview
isisd/isis_redist.c	Two targeted fixes: adds missing route-map counter decrement and map_name free in isis_redist_unset, and replaces bare XFREE with the full isis_redist_routemap_set helper in isis_redist_area_finish.

Sequence Diagram

sequenceDiagram
    participant CLI
    participant isis_redist_unset
    participant isis_redist_routemap_set
    participant route_map

    CLI->>isis_redist_unset: no redistribute ipv4 ospf
    isis_redist_unset->>isis_redist_unset: "redist->redist = 0"
    isis_redist_unset->>isis_redist_routemap_set: isis_redist_routemap_set(redist, NULL)
    isis_redist_routemap_set->>route_map: "route_map_counter_decrement(redist->map)"
    isis_redist_routemap_set->>isis_redist_routemap_set: "XFREE map_name, map = NULL"
    isis_redist_routemap_set-->>isis_redist_unset: done
    isis_redist_unset->>isis_redist_unset: listnode_delete + XFREE redist

    Note over CLI,route_map: isis_redist_area_finish follows the same path

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_{Reviews (1): Last reviewed commit: "isisd: clear route-map ref on redistribu..." | Re-trigger Greptile}

[mjstapp]

Please use a real email address in your commit sign-offs

[riw777]

code looks good ... but can you fix the sign off email?

[Evelyn0828]

Sign-off email fixed (jxshuibei@gmail.com) and force-pushed.

[Evelyn0828]

The [CI] Basic Tests failure is unrelated to this change: it's pim_cand_rp_bsr.test_pim_bsr_priority_modify (a PIM BSR candidate-RP priority test) failing on ASAN Debian 12 Part 9. This PR only touches isisd redistribute route-map cleanup and doesn't affect PIM. Looks like a flaky/unrelated test — could a maintainer kick off a re-run?

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