ipv4: use RCU protection in __ip_rt_update_pmtu()

These records connect through source-stated identifiers. Shared identifiers or dates alone do not establish shared exposure, root cause or applicability.

CVE-2025-21766 · Microsoft / collected KEV context

cve-program · CVE-2025-21766

• https://git.kernel.org/stable/c/ce3c6165fce0f06305c806696882a3ad4b90e33f
• https://git.kernel.org/stable/c/ea07480b23225942208f1b754fea1e7ec486d37e
• https://git.kernel.org/stable/c/9b1766d1ff5fe496aabe9fc5f4e34e53f35c11c4
• https://git.kernel.org/stable/c/4583748b65dee4d61bd50a2214715b4237bc152a
• https://git.kernel.org/stable/c/a39f61d212d822b3062d7f70fa0588e50e55664e
• https://git.kernel.org/stable/c/139512191bd06f1b496117c76372b2ce372c9a41

No related operational record is retained in the current change model.