CVE-2026-74490: tipc: avoid use-after-free in poll trace queue dumps

In the Linux kernel, the following vulnerability has been resolved:

tipc: avoid use-after-free in poll trace queue dumps

TIPC socket tracepoints dump queue state through tipcskdump(). Most queue-dump callsites already serialize that walk under the socket lock or sk->sklock.slock, but tipcpoll() calls tracetipcskpoll(..., TIPCDUMPALL, ...) without holding either lock.

That lets the poll trace path reach tipclistdump() and backlog head/tail dumping while another context dequeues and frees an skb, leaving the trace helper dereferencing a stale queue entry.

Stop the unlocked poll trace site from requesting queue dumps. Other queue dump trace callsites keep their existing output under the locking they already provide, while poll still emits the event itself without walking live queue members from an unlocked context.