CVE-2026-23473

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

io_uring/poll: fix multishot recv missing EOF on wakeup race

When a socket send and shutdown() happen back-to-back, both fire wake-ups before the receiver's taskwork has a chance to run. The first wake gets poll ownership (pollrefs=1), and the second bumps it to 2. When iopollcheckevents() runs, it calls iopollissue() which does a recv that reads the data and returns IOURETRY. The loop then drains all accumulated refs (atomicsubreturn(2) -> 0) and exits, even though only the first event was consumed. Since the shutdown is a persistent state change, no further wakeups will happen, and the multishot recv can hang forever.

Check specifically for HUP in the poll loop, and ensure that another loop is done to check for status if more than a single poll activation is pending. This ensures we don't lose the shutdown event.